I think any of those ideas are good. My employer gives out lots of trinkets, and some other popular ones are small swiss army knives and a AAA-cell mini-maglite flashlight. Right up there too are the ever-requested coffee cups. We have found a supplier that has a really nice-looking simulated marble look that customers LOVE. I have no idea what the minimum order or lead time is on any of this stuff, but I can surely find the supplier's name and other information.
Personally, I have a weakness for coffee cups. I have several Nikon ones.