If there's one thing I hate throwing away, it's a Sharpie. I've been using the things since childhood, and I use the ones I own today so much that I'll often wear the text off of the body; but the ink only lasts so long, and eventually they end up in the recycling bin.
Because I bought a Sharpie bulk pack years ago and tend not to linger in Staples, I didn't realize that they now make a refillable version!
The Stainless Steel Sharpie takes cartridges, has the fine point so you can write on envelopes, and has the logo laser-etched into the barrel. (I'd rather have my own name etched in the barrel, so my light-fingered coworkers in the studio won't think about nicking it.)