Tooth brush, toothpaste...just kidding. I don't generally carry too much extra for hotel stays, but I always remember to toss my SureFire (G2Z if it matters) into my suitcase and keep it on the nightstand. Make sure you lock windows and doors at night and know exactly where your exits are and you should be good. I generally stay in decent hotels in "safe" areas when I travel, so I'm more concerned with fires than break-ins and the like.

It's not necessarily a preparedness item, but a laptop can serve you well depending on circumstances. When hurricane Katrina was headed ashore, I had a family vacation planned in Dallas. (Yeah, we got some looks when we told people along the way.) We stopped over the night before in Memphis, and I was able to get a lot more news on the weather, evacuations, etc. online than I was able to get via the cable TV in the room.