I like the idea of colored coins, some remarks:

1. If you can decolor (or "wash") a coin, it would mean that anyone could simply destroy shared of your project (or whatever it is that the color represents). I don't think this is a good idea. If washing is to be allowed, it should only be allowed by the owner of the color.

2. In order to issue "shares", I would have to do one of two things:
a) Color the coins people use to by shared and send them back to the buyer.
b) Collect a bunch of coins before issueing shares so I can send those out to share buyers.

In both cases, how do I actually fund the project?