Socks in general are an all-around flawless gift because they can be tailored to just about any personality and don’t require any complicated sizing.
Mugs are the runner-up to socks in terms of best and most convenient co-worker gift for pretty much all the same reasons.
You can get staplers that go far beyond the standard Swingline. Swarovski stapler, anyone?
As you know, food gifts are always big winners at work.