When I started playing WoW I didn't even know what an add on was. I heard my guildies talking about them but had no idea what they did. I eventually ventured out and tried a few here and there (hello Quest Helper!) and now I run quite a few.
I have to say the few I cannot do without are Recount, Omen, Bartender, Titan, and XPerl.
If you're a DPS, I highly suggest you get Recount and Omen. They will save your ass! I became a much better DPSer once I got them (and some kick ass gear.... that is now outdated... damn). The other 3 are just for looks but they make it look so much better and give me more control over the user interface (UI). I love that!
Oh I totally forgot another great one: Stalker! It allows you to mark players of the opposite faction so you know when they are near by. I have several Horde on my KOS (kill on sight) list. Punks!
Here's one of the last screen shots I got of my UI before we canceled our accounts the last time. Click on it to get a larger view.
