After reviewing many of similar sites that offer rideshare, the best I found so far is RideShare.us

Although obviously not a solution for non-US events. I have tried putting similar pages into iFrame to make it appear as it is in the portal, but any sites that require login themselves have not worked for me in an iFrame. So it is just stand-alone for the event. See the listing. They do let you add some code and images which is nice. Plus it is free.

If a DNN solution comes along, please post it here.

Thanks,

Will
www.planetmaine.net