Can I just give my house back to the bank?

I have a house that I live in that I bought for $300K in 2005. Now it is worthless then $130K. I also have a condo that I bought in 2009 for about $75K that is worth about that. So my question is. . . What is to keep me from leaving my large house and mortgage and moving into my condo? It would save me about $950.00 a month? This is kind of out of spite. I really hate my bank and the fact that they did not use their HUGE bailout to help home owners. Also I'm not really worried about my credit raiting! I just bought two new cars in the last year. Plus the extra money I am saving will help pay cash if anything comes up! Any thoughts?