Recently my battery in my Asus Eee died, and I had to get a replacement. I was really nervous about getting an aftermarket replacement, but after using it for a couple of weeks, I have to say I'm really pleased with it!
Here is the battery I got: Asus Eee 1000 battery
First of all, I was really impressed with how quickly the battery came. I had it within a few days of ordering, despite the estimated delivery time.
The battery is also more powerful than the one my computer came with. Because I bought the netbook from Best Buy, it only came with the 4400 battery, instead of the 6600. When it was new, I typically got about 3 hours at the full processor speed and with the wireless on (the Eee I have allows you to turn down the processor speed to get more out of the battery). Shortly before it quit working, I was only getting about two hours out of it at best, maybe a little more with the wireless off.
The new battery is much better. After running it down fully and charging it up fully a few times to condition it, I timed the battery life at a little over four hours — and that's at maximum processor speed, with the wireless on. I haven't yet tried turning down the processor and turning the wireless off, but I think I'd probably get well over five hours out of the battery if I did.
It occurred to me the other day that with NaNoWriMo starting in a little over a week, this is a perfect time to have a brand-new, long life battery. I'll be able to easily last through all the write-ins on battery power — I won't have to worry at all about bringing my cord!