When I was at Microsoft, I actually remember Bill talking about how he's a hard person to buy gifts for. I think he said (I could be misremembering this) that he doesn't watch certain TV shows he really enjoys because he wants to be gifted the DVDs. He specifically mentioned 24.

I know he also really enjoys DVDs from the Teaching Company and has a pretty extensive collection.

I'd give him a few of my favorite books, with the hope that there'd be at least one that he hadn't read yet.

I'd also include a personal write-up as to why I enjoyed each, without giving away any important details.

A note, which will attempt to explain him how his 'Plan to Improve Our World — And How You Can Help'[1] and Open source movement are basically one and the same.

[1] http://www.wired.com/business/2013/11/bill-gates-wired-essay...

641K of RAM. More than anyone deserves!

A donation to his foundation.

An invitation to my wedding, he'd get to meet me and I'd get to meet him. It's a win - win!

I'd give him my framed MS-DOS 6.22 certificate of authenticity.

50$ so he can buy himself what he wants.

His recent Wired guest-editor issue talked about his passion for books, I'd look through the books he has and pick out a couple of my favourites that he hopefully hasn't read yet.

Books probably. And maybe if I had some spare time, an MS-DOS screenshot with "echo Hi Bill!" on it, or something.

A book, he's constantly reading.

a Linux live CD