I'm working on something like that -- I'm starting with discovering where you can go on your airline miles, but it's all visual. I'm planning on integrating suggestions of low miles tickets where your friends are. I know this isn't quite what you're suggesting, but I'll be getting there :)

I just have a launch page up right now: http://flybymiles.com - but private beta coming next week.

In the meantime check out http://wanderfly.com - they could use a much better recommendation engine, but the content is there (ie: beach for $500)