https://steamstat.us Is Steam up?
http://steamdb.info
https://github.com/jonathanlermitage/tikione-steam-cleaner Deletes installation files
http://pcgamingwiki.com
http://steamrep.com
http://isthereanydeal.com Well? Is there?
https://vacstat.us
http://steamcharts.com
http://pcgamingwiki.com
http://steamgraph.net
http://steamleft.com
http://steam.tools/itemvalue/
http://lambdageneration.com/ Valve news
http://www.valvetime.net Valve news
http://www.tf2crafting.info/
http://www.lorenzostanco.com/lab/steam/ Filter Steam libraries by tags!
https://steamid.eu
http://steamprofile.co.uk
https://steam.tools/
https://completionist.me
https://help.steampowered.com/en/accountdata/AccountSpend
https://www.mysteamgauge.com
http://www.pickaga.me
https://www.steamleft.com/
https://steam250.com/

Meta User info:
https://rep.tf
http://steamprofile.co.uk

calculate money from profiles:
https://mysteamgauge.com/

Bunch of sites about common games:
http://www.lorenzostanco.com/lab/steam/friends/ The actual best one.
https://steamparty.azurewebsites.net/ Second best one.
http://steampressure.track7.org
http://www.mysteamgauge.com/friends
http://www.gotthatgame.com/
https://steamcompanion.com/games/