YakTribe is probably the greatest website for people interested in Specialist Games: Necromunda (both old and new), Mordheim and Gorkamorka. Before the release of Necromunda: Underhive, the website held all the PDFs you could ever want about the old game. Heck, it even supported Inquisimunda (boo, hiss).
But now, YakTribe has released the tools for maintaining your gang roster and managing the campaign in Necromunda: Underhive/Gang Wars. The tools are amazing, beautifully done and easy to use. You can even add photos of your gangers to your profiles and you have multiple options for printable gang cards! It’s great!
Just go here.