A Save HD-DVD! Petition has gone up in hopes of getting Warner Bros. to rescind their decision to go Blu-ray exclusive. The number of signatures is growing by the minute, but now that New Line Cinema and HBO have followed their parent company's lead and gone Blu-only as well, it is highly unlikely - OK, impossible - that the petition will have any effect.
The two remaining studios supporting HD-DVD, Paramount and Universal, are rumored to be in negotiations to announce Blu-ray support practically any moment now. In other words, visit the cool HD-DVD website while you still can, since it's probably not going to exist much longer.