(ladybird97 calls me the International Bank of Leon. This amuses both of us.)
If you have less than $50 or so in non-US currency that you're interested in selling, I may be able to exchange it for US dollars. Drop a comment, let me know what you'd like to sell, and if it's a currency I think I can exchange, we can arrange to meet up.
With regard to buying some of my non-US currency: I have some Estonian krooni and some Hungarian forints to sell. If you are looking to buy other currencies I might be able to help you but I'll have to check. Let me know.