What would make good iPhone case art?

RedBubble, the extraordinary company that makes my art prints, cards, calendars, clothing and stickers for my online store has now started making iPhone 4 cases.

So I thought I would ask: what images from glendonmellow.com or my dA Gallery would make good iPhone cases in your opinion?  What do you think people would like to be seen carrying?  This info will help me ramp up for the holiday push to sell some wares in my online store.

Darwin Took Steps? A pink parasaurolophus? Trilobite Boy? Please comment below if you have an opinion on this!

Also: if anyone is interested in financing a giveaway of a number of cases or other Flying Trilobite swag at ScienceOnline12 in January, let's talk!

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Original artwork on The Flying Trilobite Copyright to Glendon Mellow under Creative Commons Licence.