I threw away a hard drive and forgot to wipe it first. I have heard of identity theft occurring from this kind of thing and this is especially concerning seeing as I had my bank information on it. Is this especially common or is it nothing to worry about?
Al: If you threw it in the trash, it's been buried. Nobody is combing the trash for hard drives.
You have good reason to be concerned. If someone sees that hard drive the first thing they may think is "I wonder what kind of good stuff is on there?"
If there's no way of getting that hard drive back to destroy the info yourself the first thing you should do is make some tactical changes regarding your bank accounts, etc.
Change your password and any other security information between you and your bank.
Let your bank know what happened so they can be aware of any future suspicious activity. I'm sure this is common and I'd say you have a 50/50 chance that anything will happen. I don't recommend taking a "wait-and-see" approach either.
If someone digs through the trash, finds your hard drive, and happens to be a criminal intent on using your data you could be in trouble. But that sequence of events seems unlikely.
I get used HD that have not been wiped and the first thing I do is look for music left on them and then I wipe them for reuse.
Where did you throw it? If it is going to get wet and mangled it is unlikely to be of much use to anyone.