I recently had a new product sent to me that I have found quite interesting. It is the Super Grip Lock, and is a very simple, inexpensive locking device that works on almost all dead bolts. You can take it with you when you travel and use it on most motel room doors. It will secure a door even if the person attempting entry has a bump key or the real key. If someone attempts to force the lock to turn, the key will break before the lock turns.
You can find this for sale on the internet for between 9 to 10 dollars. Just do a search for the Super Grip Lock. It is an easy to use strap that prevents the dead bolt from turning. In case of fire you can quickly remove it. I intend to carry one with me when I travel for that extra measure of safety.