I've always assumed if I was ever in this situation, I'd do the right thing and make sure it got back to its owner. Losing your wallet sucks.
Although, things haven't been so good for me lately...
**So, you're going to take it? How would you like it if that happened to you? It MIGHT happen if you do this!**
Well, karma's probably more concerning if you're not desperate. I pick it up and look inside.
I sigh and decide to do the right thing after all.