We shouldn't forget about signing up on Non-LDS sites as well, that permit LDS interaction. Many Christians won't go near a pro-LDS site, so we can answer questions in their forums. A few have dedicate sections for LDS to post such as CF.com and RF.com and Beliefnet. Besides 3 pro LDS sites [as Casslan], I am currently signed up to 8 "Christian" sites under other names. :)