http://dsp.stackexchange.com/ (http://dsp.stackexchange.com/)
It's a fairly new site for DSP Q&A, with some interesting info already. It needs more questions.
If anyone ever wanted to ask general DSP question, probably knows that there aren't any real support forums
HA can serve probably for general Audio DSP, then there could be some image processing mailing lists that can help, but I remember that I left unanswered in my quest in the past
I doubt it will be success, but then as mentioned that it's lacking topic it could turn other way around
Either way I'm big fan of StackExchange philosophy and workflow, and wish this specific Q/A branch success
Bookmark'd it for occasional browsing.
Are the answers actually any good, or is it the poorly-sighted leading the blind? Being pretty blind myself, I can't judge the accuracy of the more complex answers.