Below are our tops 3 links

Planet Namek-If you don't know about this place, you don't know DBZ. Planet Namek has one of the best overall sites including everything you need to know plus more.
King Kia's Page-Another great website which gets updated often and has a great grasp on DBZ
SaiyanZ!-this site has a very good layout and is obvious that the creator has spent lots of time on this one.

Below are other great DBZ sites

SREDBZ-This Site has a great layout and tons of great information.
3rd Season-Here you can get hundreds of movies from the 3rd season of DBZ (Ginyu and Freeza)
Karin Tower-A great overall site.
Kame House-Great site with good general info and a nice layout.
Piccolo's Island-Great section on pictures and GIFs
Saiyan Honor-A great site with everything you need in a DBZ site.
Dragonball Pictures-Exactly what it says, This place has more pictures that you could imagine.
The little Saiya-lings-Hilarious comics much like Charle Brown.
DragonballZ Temple-Another site with a great movie section
Anime Turnpike-This place has links to all of the great anime sites, not just DBZ.