Yes, there are several of these on the market now. The best known is the Labor Contraction Timer, which works on the iPhone (you access it through iTunes) and was designed by Mustansir Gulawawa; he says he did this to help his wife during her pregnancy. It allows you to make notes on contractions and record their frequency and intensity; there is now a version 2 which should be easier to use. You can also use the Contraction master on the iphone.
Google also has a version, the Contraction Timer, which among other features allows you to email the records to the midwife or health professional.
All these devices have been well reviewed, so you should have a good look at each one and see which you find best and easiest to use. If you type 'pregnancy contraction app' in a search engine you will find further information and examples.