Criminal Minds Fans are signing a a letter asking Les Moonves what he's doing to help end the strike and get negotiations underway, listing which of the CBS programs they would normally watch and pledging to boycott them, here.
If you want to protest NBC's forcing Leno and Conan to come back or face being sued for breach of contract, contact info can be found at the LJ communityWGA Supporters.
I want to be clear that the WGA is not faulting Jay Leno and Conan O'Brien for coming back--they've been great supporters of the WGA and are doing so under duress. It is quite likely that they will use some of their time on air to talk about the strike and put forth the writers' position since they are members themselves.
Of course the WGA made a deal with the production company for Letterman and Ferguson so they are not crossing picket lines. If only Leno and O'Brien owned their own production company like Letterman! I'm sure they'll be thinking about this in the future.
As always, the most up to date information about the strike can be found at http://unitedhollywood.blogspot.com/ and more excellent articles and the "Why We Write" series can be found at Deadline Hollywood Daily.