I don't have a specific app to request. I use Craigspal a lot, a program that gives advanced features to a craigslist search (but isn't open source, but these are). So, looking for a job, I can search my relevant keywords in multiple cities, and can save the search for future searches. It's an absolute necessity for me... I lost the fan on my laptop yesterday, and because of Portableapps the transition to my wife's computer has been absolutely seamless, except my inability to search craigslist with any efficiency.
On that note, maybe there's one that includes advanced searches on every program, like Google, eBay, Youtube, etc. (like Fetch! on the previous list)