Create a Sticky Topic: name it something like suggestions, for you current and future members to have a place to put their ideas forward for theirs and your forum. Test and try their suggestions, it shows that you actively engage your members, and there is the possibility they will endorse this by continually returning.
Let me give you an example: One of my forum members, suggested that we should open a solitary forum called the Gaol, and toss the moaning members into it from time to time. It went down a storm, with members moaning on purpose just to get in there to have a look, as they felt they were missing out on something. Until, one particular member was Gaoled, and he threatened us with action, because we apparently abused his basic human rights for food, medical care and visitation rights. In the end we had to release all Gaoled members on unconditional parole. The Gaol is still there, but it is now used for tourists, you know the type those one off fleeting visitors to your forum, whose expectations are so far up their own ass, that they expect to be instilled as moderators, if not super mods from the off, so we chuck them in the Gaol, and the regular members like it, as they can go in and out of the Gaol, to poke fun at those unable to get out of Gaol.
To conclude: be unique, be inventive, involve and enjoy.