So what's actually the benefit here?
Well, unlike many other file "sharing" protocols, bit-torrent uses a protocols which requires to know the others having the same file as the one you're trying to download which are called "peers" (the users). Now the more updated database of "peers" you have the better speeds you'll achieve easily.
As mentioned earlier, tracker/s are web sites which finds these "peers" using various techniques thus help your bit-torrent application to easily update the "peer" list. So the more you're able to get information from several "Tracker" web site for the same torrent, again means better download speeds, etc.
Now you can do this manually by entering the tracker web site address to your Web browser and go from one site to the next OR can get the help of a software that lets you do it in its GUI as with Torrent Search 0.9.2.1. As said this is a Gnome desktop app so up until now it didn't support Ubuntu Unity desktop. But with this release now it can also be used in Unity desktop without any problems whatsoever!.
Installing Torrent Search in Ubuntu Natty Narwhal (11.04) is pretty easy. First get the .deb package from here (the package is supported for Debian too), double click on it once the download is complete and follow the instructions on your screen. Once installed, you can access it via:
Application -> Internet -> Torrent Search.Enjoy!.