Avoiding Repeat Posts

Hi all, It seems that there might be some basic solution on this that I never received a memo on... Basically, I'm looking for a way to avoid repeat posts. If someone, for example, adds something to a bulletin board, clicks submit, and then presses F5, they're just 1 click away from re-submitting the form and posting the same information for a second time. Is there an easy way to avoid this? I've thought about using a "unique visit id" or something which gets triggered when a visitor posts, but that seems like a lot to do... Also, do you think I should look into redirecting the user once they've posted so they can't go back? I just don't know where to begin...any input is greatly appreciated. Thanks! Lewis