Keyfob Remotes
 

I wish keyfobs and remotes had battery indicators on them so you knew how low the batteries were getting. It would make things easier to change the battery instead of all of a sudden the battery going dead with no warning.

With all the fobs I had, I usually get some kind of notice that it's going dead. It'll not work unless I'm very close, or I'll have to push the button a few times, or knock it a little. That's when I switch the batteries from the stash I keep in my glovebox.