I've used audioacrobat before and it was quite easy to use. The link is
here . There is a free trial as well. I took a miniclass from Audio Acrobat although I am not sure if they still offer this.
The trial info reads: Risk-Free Trial for 30 Days! Then, a low rate of $19.95 per month. Metered at 5 Gigs of monthly bandwidth and $1.00 a Gig over. Unmetered Disk Storage!
One thing I really liked about this company was the support. Just like Aweber, they have outstanding people on staff that you can reach in a moment's notice and don't have to sit on hold going through voice mail hoops.
Good Luck!