I recently dabbled with the neat control AsyncFileUpload from the Ajax Control ToolKit which facilitates the asynchronous upload of files via the browser to the server without affecting the rest of the parent page and without causing a full postback.
I did however get an error "the file attached is invalid" when first trying it out.
Eventually fixed by adding the following to the design code:
Ed Pitt - www.EdPitt.com - I'm a Bristol, UK based freelance developer creating cool things for the web and mobile. When I'm not doing this I'm either with my burgeoning young family, mending my classic Lambretta scooter, doing up the house or dabbling in digital photography. I'm based in Bristol, which is in South West England, sort of near Bath and Cardiff :) Oh, and did I say I'm a freelance developer?