Stocktwits, a service that aggregates the stocks people are talking about on Twitter, has raised an unspecified angel round from various investors including NYC-based Betaworks, and individuals like Howard Lindzon and Roger Ehrenberg. The opt-in service scans users who put a $ sign in front of a stock ticker. In a Betaworks blog post, the firm explains the notion of social media producing “data exhaust” that can potentially be quite useful. Note that Betaworks is also an investor in Twitter itself, by virtue of the shares it received when Twitter acquired Summize.