I doubt you'll get anyone who says that salary range disclosed in a job advertisement is not a good thing, from the perspective of the job seeker.
The question you may want to ask instead is: "Does the benefit to the job seeker of having a salary range specified outweigh the loss of potential advertisers who do not want to disclose a salary range?"
If you're just doing this as a side project, with no expectation of making a business out of it, then you may want to lean more toward what benefits the user.
If you're trying to run a business and pay the bills, you might need to think more about how it decreases your potential revenue, assuming the job advertisers are the ones who are paying for your service.
One other thing: Salary range is inherently a fuzzy concept. It's possible to set limits (e.g. the range must not span more than $20K, or the range must not constitute more than 20% of the lower-end number) but then you have to take into account that an advertised salary range is not necessarily the same as what they're ultimately willing to offer you. And then you have to factor in benefits, etc., which can make salary ranges misleading.
Edit: One possible way to make salary range disclosures more palatable to advertisers is to borrow a strategy from matchmaking systems: The advertiser discloses a salary range, and the job seeker discloses a minimum required salary, to the website, which does not make any of that information public. When the job seeker submits an application for a job, they receive a notice if the advertiser's specified salary range does not meet their minimum requirements. This keeps the actual salary range out of public view and at least slightly difficult to estimate, but it prevents the job applicant from wasting their time.
I'm thinking that launching just another job board won't get me anywhere. I'll have to either a) spend heavily on advertising (which I can't afford) or b) differentiate myself from all other job boards out there.
I live in Finland (5 million habitants) and based on my research only about 5% of job ads include salary. It's not part of the culture to discuss salaries publicly so it's very well possible that companies won't be willing to go public.
On the other hand, I think it's quite promising that there are even a few companies that are already publishing their salary offers, despite most of the competition not doing it.
I see it as my job to convince them it's good for their business and start a little revolution. Maybe others will join the bandwagon?
The grandparent post is making an important point though: consider carefully which side of the market makes the rules and embrace their rules as constraints.
I spent ~8 months working on two different startup ideas in the hiring space, one with a cofounder who'd been researching it for close to a year before I came along. We also started with grand ideas of making hiring easier for the jobseeker. The problem is that jobseekers do not have money - hence why they need a job - and so all the money in the hiring space comes from the employer. Like any other competitive market, hiring is subject to the Golden Rule: "He who has the gold makes the rules."
That's why getting a job sucks so much. It's a process that's entirely designed to benefit the company offering the job, not the person seeking the job. And lest you think you can just force companies to make their hiring processes more employee-friendly (we did), consider what happens if they say no. You'll have no listings, and without any listings, you have nothing to offer the jobseeker.
I feel like the job board (yours, Monster, Dice, whoever) is in a unique position to solve this problem. You can ask each side for their salary range but then don't disclose it to the opposite side. You can then match candidates to compatible jobs and everyone knows up front that the desired ranges overlap.
This is a really interesting idea. I would expand it further... OkCupid for employment. Outsource algorithmic and language knowledge measurement to something like TopCoder and add that as a potential dimension on which to match. Education, clearances, experience: these could all be match dimensions.
Offer and demand explain a lot of phenomena. Companies only disclose sallaries when they need to, in order to seduce enough talent. Industries with a large talent pool to choose from will never do it.
Offtopic for original question, but yeah, us Finns should be more open about salaries since our tax records are already public information. But some Finnish companies are worried about publishing salaries because they think foreigners won't even apply for certain jobs if they see that e.g. Swedish companies are giving a better salaries.
...wait, if tax records are already public information - could you create a job board that doesn't require the employer's cooperation at all? Just scrapes tax return information, correlates the "employer" field (there is one, right?) with the "income" field, and displays the average salary for every job title at every company? That'd be hugely valuable information; it's not possible to build in the U.S. since our tax records are private, but it'd give a great picture of the economy and which sectors are in demand.
Multiple users could collude to determine the top of the range for a position, if that were the case.
In any case we are discussing passive job searches. I'm not going to take the time to apply to a great job if I already have a great job, in the hope that they might meet my salary requirements. I might however use salary as a metric in initial search.
The best data from a job seeker's perspective isn't a salary range, which is a signal about what to expect that you chose, it's making public but perhaps anonymous what your developers actually make, which are facts.
It's a market. Efficient markets don't have secrets.
It depends heavily on your target market and whether you can successfully influence that market. If you get a substantial number of users, and job postings on your site have a high success rate and faster responses than anywhere else, then companies may not be able to ignore your site, even though they'd prefer not to disclose salary up front. Do some trials, get those numbers, and use them prominently in your pitch to companies.
The question you may want to ask instead is: "Does the benefit to the job seeker of having a salary range specified outweigh the loss of potential advertisers who do not want to disclose a salary range?"
If you're just doing this as a side project, with no expectation of making a business out of it, then you may want to lean more toward what benefits the user.
If you're trying to run a business and pay the bills, you might need to think more about how it decreases your potential revenue, assuming the job advertisers are the ones who are paying for your service.
One other thing: Salary range is inherently a fuzzy concept. It's possible to set limits (e.g. the range must not span more than $20K, or the range must not constitute more than 20% of the lower-end number) but then you have to take into account that an advertised salary range is not necessarily the same as what they're ultimately willing to offer you. And then you have to factor in benefits, etc., which can make salary ranges misleading.
Edit: One possible way to make salary range disclosures more palatable to advertisers is to borrow a strategy from matchmaking systems: The advertiser discloses a salary range, and the job seeker discloses a minimum required salary, to the website, which does not make any of that information public. When the job seeker submits an application for a job, they receive a notice if the advertiser's specified salary range does not meet their minimum requirements. This keeps the actual salary range out of public view and at least slightly difficult to estimate, but it prevents the job applicant from wasting their time.