License Plate Frames (I'd rather be modding!)-or-(Catch me if you can)
Memo-Pads (BC logo with custom name or quote as letter head)
Pens (Bic Style)
Towels? (Beach - BIG) (yeah, maybe not)
Door Mats (You are now entering a Rice-Free Zone)
Coffee Mugs (bc logo on one side and custom pic of car on the other)
BC Antenna Balls
BC Seat Covers (with nickname of car)
HATS!!! (Maybe custom with embroidered with person'* name on back) (Black hat with person'* name in red script on back?)
Socks (Just Kidding)
Bumper Stickers (Sorta Trashy, but hey)
Small Decals (for like you computer, monitor & such)
BC Merchandise Gift Certificates
BC Custom Car Cover
BC Ice Scraper
BC Dash Cover (maybe with nickname of car along with year and sub-model)
BC floor mats (custom embroidered)
Steering Wheel Covers...
There are probably more, but i'm tired...you did say the sky is the limit...
Maybe you should make a BC Merchadise Storefront Website....you know, with pics of the items and stuff with a full catalog and such? THAT WOULD ROCK!!! That would be the coolest website in existence...besides of course its parent...Bonneville Club Forums!!
Hope I helped a bit...