Mac: Spotlight search on a Mac is one of of the best features in OS X, but if you need a little more control for hunting down files it doesn't have a lot of options. iFileX is a desktop search engine that has a set of filters to help you pinpoint files.
With iFileX, you can search by different criteria so you can find files faster. If you want, you can search by name, but by clicking the plus symbol next to each search box you can add date and size filters to the mix. Your results include hidden files and package content, so it makes it easy to see what's really on your hard drive. It's not exactly a replacement for Spotlight, but it's a great tool to filter search results if you're hunting down something specific. It's a free download from the developer's site below.
iFileX | OSX Bytes via Addictive Tips