From Beagle‘s website,
“Beagle is a search tool that ransacks your personal information space to find whatever you’re looking for. Using Beagle, you can easily find: documents, emails, web history, IM/IRC conversations, source code, images, music/video files, applications and much more…”
Beagle is IMHO the best thing since slice bread (or rather since Ruby). By the way, Beagle runs under Mono, the open-source implementation of the .NET architecture.
Beagle is basically a server process (called beagled) which quietly indexes all your files and a graphical client (called beagle-search) which allows you to search using keywords and boolean operators. beagle-search is a Gnome application and, as a result, does not integrate that well with KDE (which I use). I’ve found a great alternative in Kerry:
Kerry is functionally equivalent to beagle-search but is a KDE application and therefore integrates really well. I’ve bound Kerry to the ‘Pause/Break’ key on my keyboard and I can just open it by pressing that key. I really feel I’m more of a power (to the square?)-user now…
Try both and you’ll be hooked. That’s the future of computing!
PS: To install kerry (and, of course, beagle) in either x86 or x86_64 (AMD64) (K)Ubuntu (I’ve tried both), just open a console and type:
sudo aptitude install kerry
and launch kerry like any normal application (it’s in Utilities). Configure it to launch beagled everytime you log in, bound it to a nice key (I’ve used Pause/Break) and have fun 
Search engines, what would we do without them?
What’s great is that I’m rediscovering some old documents I downloaded or even wrote myself
Beagle works really well and I should have installed it years (?) ago