Best way to produce a percentage bar

I need to produce a simple graphic which is a simple rectangle (bar) with a variable portion filled in to denote a percentage.

What is the best way to achieve this? I had a look at the .net charting tools but the nearest I could find to what I needed was the barchart which didnt quite seem to meet my needs for a single value.

Any ideas?

You could always try using jQuery UI's progressbar.

I've used it on a few occasions and it works quite well.