I saw an ad for what is essentially a flat Swiss Army knife. It had several of the useful tools, including a knife and scissors, but they slid into something that was about the depth of three credit cards. I thought it sounded good - and then I thought about losing it forever if I flew and forgot that it was in my pocket.
I know, in the scheme of things, that wouldn't be a big deal. But it would be to me. Why can't the TSA mail stuff back?