Cher is one of many big names who've signed on to a campaign called Sound Off for Autism Speaks, which will raise money to support autism research and advocacy.  For $299, the legendary diva will record the personalized voicemail message of your choice. The only limit: it's got to be either 20 seconds or 250 characters of text.

 

Other stars participating include Jack Black, Peter Dinklage Mark Hamill, Jim Parsons and Batman himself, Adam West.

For more information visit Autismspeaks.org