Disclaimer: I do not control, or necessarily agree with all of, the content contained in the following:
Radicalizing the Romanceless – An article about how Nice Guys really do have a hard time.
“Shyness & Love” Book – A 1987 book (700+ pages) by Dr Brian Gilmartin analyzing Nice Guys, before the term even came into being. Based on the results of a large correlational study, it describes how they came to be, common traits, and how they can turn things around & succeed at dating.
The Rules Revisited – A frank blog that advises women on how to attract men (written by a man). It’s kind of like the opposite of this blog.
Purple Pill Debate Subreddit – Not safe for work. The most honest forum I have found so far for debating the effectiveness of two opposing dating approaches – The Blue Pill (“Be yourself”) and The Red Pill (improving yourself with an unfortunate & unhealthy dose of sexism & bitterness). Update (Aug 2015): Unfortunately, this forum has started getting too biased toward Red Pill thinking.
Punching Morpheus Subreddit – A politically-correct version of the above Purple Pill Debate subreddit. It contains less substance than Purple Pill but has some useful viewpoints still.