Admiral Ackbars CCG Trade Page: Trading have and needs for various collectable card games including Star Wars, Star Trek and Middle Earth.
Mahasamatman's Universal Trading Page: Online trading for many different games.
Steven's MtG and MECCG Trading Site: Buy and trade Magic The Gathering, Lord of the Rings and Middle Earth cards.
Trade Cards Online: Find other people interested in trading with you, and be notified whenever the cards you are looking for are available for trading.