Figure Companies

Games Workshop-Needs no introduction
Gripping Beast- Make excellent dark age miniatures, expanding into ancients,  great value for money.
Foundry- Are producing new highly detailed fantasy range and have a huge ancients range.

Other Good sites

Warhammer Players Society- All war gaming clubs should join WPS, they organize events/tournaments almost every month round the country, has a great forum and professional magazine which can be downloaded.
Stuff of Legends- Not a flashy site but has the largest resource of figures old and new from games workshop and other manufacturers, together with scans of the old citadel catalogues, great shots from GW HQ and various games days.
Portent- A good source for all games workshop rumors, and news. Usually you get sneak peeks at unreleased figures too.

Warhammer Ancients

Yahoo/WAB- A great news group with over 650 members discussing all aspects of WAB.
MiniMatters - A nice site dedicated to miniature wargaming and painting by Geert Horvers, with useful information on ancient gaming and resources.
Ancient-battles - This is for our German friends who find there way to this site looking for GrippingBeast Pictures, here is an indepentant stockest who sells lots of 28 mm figure ranges, paints and tranfeers. (site is in German).

Warmaster

Warmaster -The official warmaster site run by Rick Priestley.
Brumbaer - Home of the Warmaster army generator and excellent paper buildings/castles for warmaster.
Yahoo/warmaster - Another great news group with over 900 members discussing everything warmaster.
Warmasterworld - A new (2002), well designed site taking up where maximumwarmaster left off, providing a central location for all that is warmaster. This site is updated at least 3 times a week, with monthly competitions and a 'opponent finder' database.

Painting

Yahoo/painting - A must visit group for experienced to beginner painters it has over 800 members, and there are very good/professional painters on the list always willing to give advice, share photos of newly painted figures.
Littlebrush - A good site with plenty of painted figs and a good painting guide too.
Miniature-painting - Another good site for inspiration and great galleries
Charger - This guy has done some painting guides for Ral Partha Publishings e-zine, he has some of his guides on his site, with some great galleries.