What memory card would be best for a 10MP camera?

I would say get the most memory you can afford. That would be the issue for me. The more memory, the more it costs.

If you plan on downloading your images every night, a couple of 2GB cards will do you fine. That’s the professional opinion, since cards crap out from time to time. Otherwise, get a big fat card, and hope it doesn’t get corrupted.

You are better off with several smaller cards than one large one. If you lose one, or one fails, then you have lost fewer images. I usually carry several 4 GB cards, and use several 8 or 16GB as a storage medium. You can transfer data between cards with a simple card duplicator from eBay. If you want more security look to some of the photo storage hard drives from companies like Epson and Phototainer. They can hold up to 160GB and display the images as well. I carry one of those if I don’t have a notebook computer with me. The number of images per GB should be in your manual – it varies depending on the settings, RAW, JPEG, fine or standard etc.

2GB memory cards are usually pretty inexpensive, and you can always carry an extra if need be, or maybe one specifically for video only.

But a 2GB card would be more than sufficient.

Bigger is better, although @DarkScribe raises a great point. Then again, I could just as easily argue that by having multiple flash cards, you raise the chances of one getting lose or lost, versus having one huge card that never leaves the camera.

You can approximate the number of shots per card by doing the math: take your average picture filesize, multipy the gigabytes of the card by 1024 to convert it to megabytes, and divide that huge number by the average picture filesize.

A 2GB card will give you around 350–500 pictures depending on your camera settings (how high quality the photo is, for instance). You can easily push that higher by reducing your settings, and make better quality photos (but reducing the number you can save) by making the pictures high quality. Though you don’t need super high quality unless you want to print out a HUGE print.

In my experience I have never had a flash card of any brand or type die on me.

My recommendation: if you will be downloading your pictures nightly, you’ll be fine with a 2GB card. If you won’t be downloading, go for the 8 possibly, or two 4s if you feel confident that you won’t lose any of them.