Buy a digital voice recorder. I have an Olympus. We’re talking $20 -$30. Now, besides using it for the job you described, you might find as I do what a fantastic tool this is. I use mine all the time. For example, when driving there is so much dead time and things, random things come to mind. Things to look up, people of the past and what happened to them, things I need to get done, things I see on the side of the road that need attention (burned out street lights). Also, as I walk around my house during the week, I note things that need to be done like burned out lights, broken appliances, unshined shoes…such little things that if I didn’t write or recite them down, they’d never get done. Then on Saturdays, I replay my “list” of “to do“s and get all these little things done. A digital voice recorder is absolutely fantastic. These are things in the past a person would have jotted down on a piece of paper but a recorder is much faster and very easy to use in the car. You don’t need a ton of memory either. When you record, all you need is a key word to remind you later.
Here is the one I have
http://www.google.com/products/catalog?q=olympus+digital+voice+recorder&hl=en&safe=off&client=firefox-a&hs=tzO&rls=org.mozilla:en-US:official&prmd=imvns&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&um=1&ie=UTF-8&tbm=shop&cid=10704691692874320812&sa=X&ei=uWaUT_vYG8PQ2AWp1rX2BA&ved=0CKwBEPMCMAI
and here are a bunch more
https://www.google.com/search?q=olympus+digital+voice+recorder&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a#q=olympus+digital+voice+recorder&hl=en&safe=off&client=firefox-a&hs=pzO&rls=org.mozilla:en-US:official&prmd=imvns&source=lnms&tbm=shop&ei=mmaUT7jWLIeC2wXr2Y3_BA&sa=X&oi=mode_link&ct=mode&cd=6&ved=0CGUQ_AUoBQ&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=e040e1c25aedeb6f