Fair Radio - Catering to Hams Fair Radio has lots of bargains for tube enthusiasts
Triode Electronics - Ned supplies quality tubes & tube "stuff" at great prices
Magnequest - If you want some of the world's best transformers, call Mike
New Sensor - Consistently high quality tube supplier
Svetlana - More high quality tubes and tube data
Used Test Equipment List - If you're in the market for reconditioned high quality (e.g HP, Tek, Fluke, GR) test gear go here and be prepared to spend some time. You'll find detailed descriptions for the equipment you are considering and eventually find a good buy.
AST Global Marketing - High quality test equipment @ great prices & service
A Used Test Equipment FS Newsgroup
Another Used Test Equipment FS Newsgroup
Digi-Key  - Good selection of common electronic components
Mouser Electronics- Similar to Digikey but superior customer service
MCM Electronics - Another parts distributor but with a better selection of tools, test equipment and consumer electronics repair specialty items - a must have catalogue