Training & Nutrition - Special computer needed for logging miles on Trainer?

Excuse the possibly stupid question, but every computer I've ever owned has hooked up to the front wheel. I plan on doing some training on a stationary trainer soon, and am wondering how the heck I'm supposted to log miles? Is there a particular wireless computer that hooks up to the rear wheel?

Not sure on wireless, but the CatEye Astrale 8 can be bought with a rear wheel sensor (wired), and also displays cadence.

Well, some would say that trainer "miles" aren't real, and should not be logged as such. Without wind resistance and hills, it's not easy to calculate equivalent mileage on a trainer.

In my CycliStats ride logger software, trainer rides can be logged with time only, or with time and distance. I'm under the impression that most users of the program log only the time they spend on the trainer.

I used to use a cheap Performance brand computer that was wired and had a rear wheel sensor and cadence. I think it was this one: http://www.performancebike.com/shop/Profile.cfm?SKU=4024
Now I just log time.
There's a wireless computer with a single sensor that goes on the rear wheel stay for both cadence and speed/distance. I don't remember the brand but it was in the last Performance or Nashbar catalog I received.

I'm very happy with my Cateye rear wheel sensor cycle computer.
I believe it's the current Astral model. I like the cadence feature too.

I found mine on ebay for ~$27 shipped.

Personally, I think trainer miles should count for 2 or 3 times the amount of actual riding outside. The longest I've ridden on the trainer is 14 miles. The longest outside is 138 in one day. I have averaged centuries at 18-19 mph, and my average on the trainer is usually 12-13. Now using the life cycle is a different story. Those miles should only count for 1/3 of regular miles. There is hardly any effort to riding a stationary bike at the gym.