UltraSearch is an easy-to-use free search tool which can locate files and folders almost instantly.
The program achieves its high performance by directly accessing the NTFS Master File Table (MFT), which holds details on every file and folder on your PC. And so it's able to return results immediately, typically in around a second or two, without having to waste time or resources building an index: just enter a keyword and watch the results appear.
But the disadvantage, of course, is that the MFT only indexes file and folder names. So you can't search for JPEG metadata, emails or other file content - it's strictly names only.
In addition, the program only works on NTFS-based drives. You probably won't be able to use it to check the contents of, say, your USB flash drives, as they're likely to use a FAT-based file system.
UltraSearch is still useful for its extreme speed, though. And if you know you're going to spend a while searching only for particular file names, then its inability to show anything else is a plus, as it'll help you zoom in immediately to access the files and folders you need.
Version 2.0.3 "increased search performance".