IMSLP/Petrucci Music Library - Free Public Domain Sheet Music
TAP Music - Specializing in brass music and recordings
International Trumpet Guild - If you enjoy trumpet, you should be a member!
Trumpet Herald - A great resource, but don't believe EVERYTHING you read. It is just one source.
Doctor Valve - Trumpet repair
Charlie's Brass Works (Charlie Melk) - Trumpet repair and customization
Theta Music Trainer - Ear training games
Great places to buy new and used trumpets
Horn Trader - New, used, and vintage
Trumpet Trader - New, used, and vintage
Dillon Music - New, used, and vintage
Wichita Band Instruments - New, used, and vintage
Thompson Music - New, used, and vintage
Woodwind and Brasswind - New instruments, mouthpieces, and supplies (for all levels)
Rayburn Music - New, used, and vintage (Call for current inventory)