I use the Xtreme MOD. There is also ScarAngel (a mod from Xtreme) and MorphXT as the most important I guess. But I believe Xtreme is the most used.
You could set 'Global' for searches. This finds what you wants in all the servers instead in only the one you are connected to. The KAD searches in the KAD Network, but you don't have to. When you are downloading a file, it takes sources from Kad too.
Be sure to update the Servers List from gruk.org by pasting this on the 'Update from URL' box at the right area.
Sorry for my English, it's not my mother language as you sure noticed.
I'm sorry for the double post, I tought I could edit. I'm kind of new here.
There is a comparison between some Mods that would help you decide which one to use.