I think a timeslip feature would be great. For a model look at the feature on www.dsmtuners.com (although the forum is broken right now, now that I look at it ).

It has a dedicated section where you can browse timeslips with fields for time @ mph, type of car, a short mods list, etc. It links to your personal car profile which has fields for mods, pictures, etc, cardomain stuff. The times are links to pictures of the timeslips, a timeslip isn't considered valid unless you have a picture of it linked and you can report phonies. The best part is that the times are listed under everybody's names in a field like the Car: field or Location: field as a link to the picture of the timeslip. It shows a blank time unless you have a picture loaded.