A write in vote isn't an option in most states.
Even if there is a space provided on the ballot for write-ins, the vote is usually not counted or even seen. If RP doesn't get the nod for the GOP, I will probably vote for the Libertarian candidate. There is no way I will ever vote for McCain, Obama, or Clinton.
IMHO, a vote for a third party candidate will be a protest vote that counts. If you look at the results from the senatorial elections two years ago, they clearly show that the Libertarian party drained votes from the GOP and cost them control of the Senate.
If the GOP ever wants my vote, they will have to come up with candidates that respect the Constitution of the United States.
I hope this group (ronpaulforums.com) stays together in some fashion to continue the fight for liberty. We have been a powerful force.