A few years later, I'll make this comment:
When it comes to cameras, which I tend to have a fair few of, I'm pretty lax about lending and letting others use stuff. Things like my Nikon 14-24mm f/2.8 are sort of exotic to a lot of photographers, and I've let coworkers who I determined to be trustworthy borrow it for a weekend or whatever. I have one particular co-worker who I lend stuff to quite often-a while back he was complaining about how he was missing shots with his D7000/80-200mm f/2.8D, something that didn't particularly surprise me. He was debating about going full frame as well as upgrading that lens, so I handed him my D600(basically a full frame D7000), D3s(older pro class body), and 70-200mm f/2.8 AF-S VRI for a long weekend-after using both bodies, the lens, some of his lenses on my bodies, and my lens on his D7000, he turned around and bought a D4 and 70-200mm f/2.8. Everything was returned to me in perfect condition. The same guy also lent me his 85mm f/1.4D a few months later when I had an occasion to need it-a sort of standing quid-pro-quo agreement between us for his ready access to anything I have that I'm not using.
When I do loan a camera in particular out, I know I'm always taking a chance, but in general if something happens its not the end of the world. There are ones to which I have some sentimental attachment and wouldn't loan, but they're also not things people would likely want to borrow.
I have enough spares of things like MacBook Pros that I sue for specific purpose but that I can bear to be without for a few weeks at a time-I've also been known to loan those to people in need of one. With that said, depending on who is borrowing, they GENERALLY get their own limited-priviledges account just to cover myself and so that they can't access file vaulted stuff.
My main MacBook Pro is a BIT of a different story just due to the amount of sensitive information on it. The only other person who uses it occasionally is my girlfriend, who rarely travels with her laptop(it's rare that I DON'T) but occasionally needs to do something that she can't do from her phone. She does have her own account on my laptop, but it has full admin priviledges so she can see/do anything. I mostly made it because I got tired of her complaining that about the fact that my trackpad scrolls in the direction that Steve Jobs intended

(i.e I don't use "natural scrolling"). Her account is mostly so that it can scroll in the direction she claims is correct without my having to go in and change it
