Design and history of classic transistor radios on this site by James Butters.
http://www.jamesbutters.com/index.htm

Collectors Weekly transistor radios page:
http://www.collectorsweekly.com/category/radios/transistor.php

Vintage transistor (and other) radios, TVs, audio equipment, parts, and more for sale:
http://www.vintage-electronics.com

Aldo Andreani's giant list of links: 
http://sites.google.com/site/aldoandr/

The Transistor Museum--Jack Ward's site "dedicated to preserving the history of the greatest invention of the 20th Century."
http://www.transistormuseum.com

John Pelham's web museum "Radiophile.com."
http://www.radiophile.com/transist.htm

Radio Wallah--a transistor site with great pictures and info.
http://www.tabiwallah.com/radiowallah/index.html

Childhoodradios.com—Ron Mansfield's site with message board and more.
http://www.childhoodradios.com

Radio Gort: "The biggest Danish radio collection on the internet"
http://radio.gort.dk/

C.E. "Sonny" Clutter (The Radiola Guy)'s sale list.
http://www.radiolaguy.com/transistors.htm

Radiomuseum.org: Photos and data for (mostly) tube radios.
http://www.radiomuseum.org

Sarah's Transistor Radios.
http://www.transistor.org

Robert Davidson's Transistor Radios in galaxy M31.com 
http://www.abetterpage.com/transistors/trans/1trans.html

Lello Salvatore's transistor site. A real enthusiast! 
http://www.alltransistor.it/

Enrico Tedeschi's "Old radio Digital World." 
http://www.brighton-uk.com

eBay's Transistor Radio listings: 
http://listings.ebay.com/aw/listings/list/category932/index.html