Yeah I bought a couple of USD Erupters out of hobby/interest in August, they've been mining almost non-stop since. I've watched my pool on BTCGuild go from less than 70 Th when I started, to nearly 1.5 Ph today. So my daily earn is almost going to fall off their decimal scale soon when I start earning less than 0.00001% per shift...
But ... I've mined around .25 BTC, and haven't sold any of it yet, so I'm on track to break even as it stands. I wouldn't care if I didn't anyway, more out of technical interest.