Lesa's Book Critiques. She reviews (mainly) mysteries, but also has some great articles and guest posts essential to writing in this genre.
First of all, you'll keep up-to-date on what's being published in your genre. That's not an easy feat on your own. It's just not possible to keep up with all the new releases, while getting your own writing done. That's why Lesa's blog is so effective. You can read reviews of everything that's new, and just select a few to read yourself. If you write in another genre, do a search for blogs that review your particular interest area.
Have you ever wanted to pick the brain of a forensic artist? (not literally) How about consulting with a handwriting analyst? These are the things that mystery and crime writers salivate over. Give them a book of poisons, or a list of ten ways to kill someone with a ballpoint pen, and they're happy.
Besides reviews, Lesa post frequent interviews with top authors, like women who kill, and links for those who write in her favorite genres.
Would you like to join some like-minded writers? Check out these groups:
Mystery Writers of America
Sisters in Crime
International Thriller Writers
Suspense Romance Writers
American Crime Writers League
The Crime Writer's Association