A website with proof techniques or math methods is Tricki.org.
Wiki on Timothy Gowers role in Tricki
Tricki.org is a Wikipedia-style project collecting methods of mathematical problem solving conceived in 2008 and launched by Gowers, Olof Sisask and Alex Frolkin in March 2009.[8] Terence Tao and Ben Green are among those to have contributed articles.[9]
Timothy Gowers announcement Tricki fully live
Terry Tao announcement on Tricki now live.
Timothy Gowers 2010 on whether the Tricki is dead?
It appears to have a little activity in 2012 and before that in 2011.