comments on relevant sites is a good way to validate a persons ideas, domain knowledge, and thoughtfulness, but my main contribution's have been to TC, AVC, Flickr, and others, so I get no benefit from that here. Maybe a hot idea for a simple web 2.0 startup would be an aggregation tool of all comments by a user across the sites they use. Could work well with OpenID.

Maybe I'll add that to the question in the application that asks for "any other ideas you've considered" :