When I recently got back into freecycling, I thought it was a while since I got involved with the movement, that there would be some other web sites beside The Freecycling Network (TFN). I didn't look too hard and settled back with TFN. In these days of Facebook, Twitter, instagrams etc, TFN, at least the Brooklyn and NYC groups that I use, are rather quaint with their Yahoo!Groups interface. No attachment, a little delay waiting for approval by moderators, message list order sometimes seemingly out of whack. But I quickly got used to it. It's actually not bad, just post a message and wait for email responses. You can even send email to some group address to post offers. Still, there must be other services out there, and as Allan from AnyGoodToYou wrote in that service's blog, there are. I checked out the sites Allan mentioned, including the ones found in Wikipedia. I also happened upon other services. So there are alternative services to TFN, but none matching TFN's breadth. Some are limited geographically, others are just alternative interface to the same TFN data, and some are too quiet to be considered active. For my visits, where applicable I only look for Brooklyn, NY and nearby towns, usually NYC (supposedly the five boroughs of the Big Apple).
http://trashnothing.com - Freecycling Network with a more modern interface
http://www.reusemoose.com - mostly Australia? I did find a Brooklyn group but it has very little to offer.
http://www.anygoodtoyou.com - UK-based for now
http://freecycleplus.com - relatively new, few listings
http://www.reuseitnetwork.org - Brooklyn and NYC groups are Yahoo!Groups like Freecycle, no interface improvement, new listings in the single digits.
I do recommend you check out these alternatives to TFN. Competition is good. Maybe your particular city has a lot of activities.
I would not be surprised if I missed some web sites for freecycling. Do let me know in the Comments!