Alrighty... For those of you outside the know, and those of you looking for alternative bitz for your minis, have I got a treat for you! Please bear in mind that I'm looking at these through 40k colored glasses, and that these are reviews of the items themselves, although I have gone through and looked for reviews where I could.

Maxmini.eu
28mm goodness for head swaps and equipment places. Imperial Guard, Space Marines/CSM, Ork and possibly Eldar players will all find some nice options in the way of heads, weapons (check out the T-gun set and bust out the green stuff... I smell an Ork "Mob" taken waaay too literally here...) and flavor bitz. Cast Resin Pieces.

Pig Iron Productions
IG and Tau players, you might wanna check this site out... Head Swaps and bodies for a pretty fair price. Full Resin Kits & Models (Tourney players, check with your organizers to see if it will be an issue!) are available, as well.

Armorcast
That's right, Armorcast. The company that was putting out slightly less detailed titans and superheavies that you can still buy on ebay holds a special place in my heart... The guys that run it kinda frequent my FLGS... Good guys, the group of 'em, and truly passionate about the quality of the products they sell. With everything from steampunk to future-gothic as well as "special effects" pewter castings and a mind-boggling array of conversion bitz and decal sheets. Truly some great stuff from these Cleveland boys.