If you can't find it by using one of these search systems, it probably can't be found. Remember to try to narrow down your search, it's a big universe out there. Read the help files associated with each system if you don't realize why you're getting a certain kind of result. Boolean logic (especially AND & OR) will help with just about any of the below systems.
The first site you may want to travel to is Search Engine Watch. There you will find the latest information concerning search tools, ratings, reviews, and more.
Legal/Law
Invisible Web Resources
Meta-Searches
People Finders