Being a huge fan of anything that makes my life easier, I’ve been using scriptaculous for a while. I recently found stickman’s accordion and was very pleased with its performance compared to the asp.net ajax accordion. (Mostly I was pleased stickman’s version shows all content with scripts off while the asp.net one hides it.)
The only feature that was better in the asp.net version was the ability to close panels. So I added it.