1) A smartphone. I use it to record notes and random ideas as they strike me, read & answer emails, find directions, and all that other good stuff. The note taking is a huge advantage though.
2) An online calendar. For better or worse, I've freed up my brain space in favor of an online calendar to track my meetings, appointments, events, etc. I don't have to keep those in mind anymore. Personally, I love this, but it does make me overly dependent on the online calendar.
3) Goldtouch keyword. I love this thing. I was trying to stay away from brand names in my list, but I didn't know how else to describe it. It folds down from the middle allows you to touch-type in a very ergonomic position, at least for me.
4) Duct tape. It truly can repair anything physical. Just fixed my fan with it.
5) A towel. You always need to have a towel ;)