Check out this recent story by Sarah Hollander from cleveland.com, which ran on 4/11/08:
Rideshare seeks to link bicycle commuters
Bicycle commuters can now search for fellow riders through OhioRideshare, a program heretofore focused on matching carpoolers.
By creating an account at www.OhioBikeBuddies.com, cyclists can see if anyone is traveling at similar times and to similar destinations. Users can indicate whether they prefer a male or female companion and would communicate directly through email.
Because this is a new feature it might take a while before the database grows and matches are available. The program's organizers encourage users to revisit the site frequently.