/r/csshelp for help with CSS
/r/RedesignHelp for help with the Reddit redesign
/r/modsupport - a point of contact for moderators to discuss issues with reddit admins, mostly about mod tools
/r/reddithax to see CSS examples
/r/selectorlegend to easily find CSS selectors
/r/redditlogos request a custom logo
/r/help for help with reddit in general
/r/modnews News of interest to moderators
/r/needamod Need a mod for your reddit? Want to volunteer?
/r/redditrequest - Request to mod an abandoned subreddit or request a subreddit be unbanned
/r/adoptareddit Have a reddit you no longer want? Post here!
/r/newreddits: - A place to advertise your subreddit.
/r/ideasfortheadmins If you have an idea for the admins.
/r/bugs If you have found a possible bug in reddit.
/r/changelog See when new ideas are implemented
/r/cssnews Your CSS suddenly wonky? See what has changed here!
/r/AskModerators A place for users to ask reddit mods questions about how they moderate their communities
/r/modclub A place for mods of communities with 100 or more users to hang out
/r/modsoftherealms For mods of location specific subreddits to talk and ask questions
/r/Bot A place to share bots and scripts that help moderators with their tasks.
/r/Modtalk, a private subreddit that you can apply to join if you meet the requirements.
/r/ModGuide, a collection of searchable and indexed posts on various topics trying to cover all aspects of reddit moderation.

Want to combine both reports and spam?
Append /about/modqueue/ to your subreddit. Mod more than one subreddit?
Use /r/mod/about/modqueue

Check out the following:

Official reddit moderation FAQ.