Originally posted by Modiga-Disabled:

Third Party Trading Sites

Games and Coupon trading sites

• Steam Exchange[www.steamexchange.com] (limited support for in-game item trading)
  
• Uberdeal[www.uber-deal.com]
  
• Steam Trades[www.steamtrades.com] (support for in-game item trading)
  
• TF2 Outpost[www.tf2outpost.com] (Strong support for in-game TF2 and Portal 2 item trades as well)
  
• {LINK REMOVED}sGs Marketplace
  
• Reddit: /r/SteamTrading
  
• Reddit: /r/SteamGameSwap
  
• Reddit: /r/SteamIndieSwap - For indie games

Team Fortress 2 Items trading sites

• TF2 Trading Post[tf2tp.com]
  
• SourceOP[sourceop.com]
  
• Unusual Trading Community[www.unusualtradingcommunity.com] - Specialises in trading unusual hats.
  
• TF2 Metal Market[tf2mm.com] - Metal trades only.
  
• TF2 Items[www.tf2items.com]
  
• TF2 Trader[tf2-trader.com]
  
• TF2 Empire[tf2-empire.net]
  
• http://www.tfportal.de/items/trade - German and English language trading site.
  
• GhastlyGibusGC[ghastlygibusgc.site40.net] - Forum, has sections for Portal 2, games and coupons as well.

Dota 2 Items trading sites

• The Dota 2 Trade Center[www.dota2tc.com]

Other

• Steam Gifts[www.steamgifts.com] - Not a trading site but allows users to give away gifts.
  
• TF2 Raffle house[tf2r.com] - Allows users to raffle away TF2 items.
  
• SteamRep[www.steamrep.com] - Scammer report site
  
• MMOSpawn[mmospawn.com] - Hosts game give aways.

Significant Steam Groups

• Traders Guild
  
• Wicked Afterlife Trade Group
  
• Where Traders Rocks

Here are some alternative sites to use to advertise trades. Feel free to post or PM me any additions to the list. Also feel free to discuss these or other trading sites in this thread. Any trade posts made within this thread will be removed.

Please note you use these sites at your own risk and that all trades should be made through the Steam trading system because of this.

Originally posted by Felix:

http://forums.steampowered.com/forums/forumdisplay.php?f=1189

Originally posted by Modiga-Disabled:

Third Party Trading Sites

Games and Coupon trading sites

• Steam Exchange[www.steamexchange.com] (limited support for in-game item trading)
  
• Uberdeal[www.uber-deal.com]
  
• Steam Trades[www.steamtrades.com] (support for in-game item trading)
  
• TF2 Outpost[www.tf2outpost.com] (Strong support for in-game TF2 and Portal 2 item trades as well)
  
• {LINK REMOVED}sGs Marketplace
  
• Reddit: /r/SteamTrading
  
• Reddit: /r/SteamGameSwap
  
• Reddit: /r/SteamIndieSwap - For indie games

Team Fortress 2 Items trading sites

• TF2 Trading Post[tf2tp.com]
  
• SourceOP[sourceop.com]
  
• Unusual Trading Community[www.unusualtradingcommunity.com] - Specialises in trading unusual hats.
  
• TF2 Metal Market[tf2mm.com] - Metal trades only.
  
• TF2 Items[www.tf2items.com]
  
• TF2 Trader[tf2-trader.com]
  
• TF2 Empire[tf2-empire.net]
  
• http://www.tfportal.de/items/trade - German and English language trading site.
  
• GhastlyGibusGC[ghastlygibusgc.site40.net] - Forum, has sections for Portal 2, games and coupons as well.

Dota 2 Items trading sites

• The Dota 2 Trade Center[www.dota2tc.com]

Other

• Steam Gifts[www.steamgifts.com] - Not a trading site but allows users to give away gifts.
  
• TF2 Raffle house[tf2r.com] - Allows users to raffle away TF2 items.
  
• SteamRep[www.steamrep.com] - Scammer report site
  
• MMOSpawn[mmospawn.com] - Hosts game give aways.

Significant Steam Groups

• Traders Guild
  
• Wicked Afterlife Trade Group
  
• Where Traders Rocks

Here are some alternative sites to use to advertise trades. Feel free to post or PM me any additions to the list. Also feel free to discuss these or other trading sites in this thread. Any trade posts made within this thread will be removed.

Please note you use these sites at your own risk and that all trades should be made through the Steam trading system because of this.

This post can be found here: http://forums.steampowered.com/forums/showpost.php?p=27868520&postcount=1