Some websites and references that I find useful/interesting in no particular order..
A blog I read or at least glance at almost daily:
the morning paper
Join these two organizations:
ACM (Association for Computing Machinery)
Percona Database Performance Blog
Also take a look at Baron Schwartz’s blog
Miscellaneous Performance Sites:
Brendan deserves his own section and, I suppose he’s most famous for his Flame Graphs and his hilarious Shouting demo.
Brendan Gregg’s Blog
Brendan D. Gregg