Originally Posted by
tempocyclist
Do you mean like the "cue sheets" that some pros stick to their stems or bars, listing climbs, important race points, and/or fuelling times?
I've only ever done it once, when I was scouting out a loop of a gravel course. Actually found it pretty handy as it gave me a good idea of when the climbs were approaching.
Most Garmin GPS units will have ClimbPro. You can see the climbs listed on the route beforehand, and when you get to them, it will tell you how much longer you have to suffer.
Important points (rest stops, etc) can also be noted on your route and it will notify you when you approach one.