The great thing about side projects is that they only get better -- your code stays written, your marketing snowball gets better, age and inlinks bring your rankings higher, etc. (If your business plan does not have these features, for example if you are planning to sell iPhone applications which have a shelf-life of cut apples which have been soaked in agar[1], you may wish to reconsider.)

2006: $1k of bingo cards

2007: $10k of bingo cards

2008: $21k of bingo cards

2009: ...

[1] Don't try this at home, kiddos.