In reply to planetmarshall:
An article on ClimbStrong.com about quantifying boulder problems made me think about this. This calculates four things: number of problems climbed, a total number of grades added together (using the V system is straightforward), the average grade climbed, and the 'session density' based on the time taken.
With a phone or tablet with you, you could tick off what you'd done as you go along with a clock timing your session too. The results would be stored and dated and could be output to graphs to map your progress.
Unlike weight training seeing improvement from session to session is not so easy with climbing. It's not as simple as just counting reps and sets and going up a grade tends to happen fairly infrequently. However recording what you do like this I think you could see improvements more regularly. Seeing such improvements motivates one to keep going and also gives one goals for each session.
The same thing would work for routes too of course.
I suppose a developed app would also have input for exercises too, campusing, weights, rings etc.
The article:
http://climbstrong.com/articles/20150313