I've found what looks to be the perfect TiBook case.
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There isn't a whole lot of padding; it is *just* larger than the tibook in all dimensions. There are more protective cases out there, but this should at least keep your 'book from getting crushed while transporting it. The case is made of aluminum and does not bend if you apply pressure. It is also very lightweight.
For those in the SF bay area, they have it at the Sunnyvale ComputerWare store for $100.