Former Investment Banker (thanks derivatives for getting me laid off, I really enjoyed school for nothing) now a business author and "offline" management consultant/turn around specialist. I use IM to supplement income. It's a good rule of thumb to always have 5 streams of income, I tell almost every business owner that when i work with them. I would link to my blog but I know it would be copied and pasted into articles by the time I finished writing this.
The only problem is, right now, I completely suck at IM, so that income stream is about $30/month. LOL.