I haven't found any good gui download accelerator. And i frequently use axel with firefox and its pain to have many windows opened at a time. And i have to save the url somewhere if i want to pause and restart the url later.
So i thought of making my own .I have written the program in Qt4.
My idea was to have a common GUI for most of the command line accelerators available for linux like
1) axel
2) proz
3) wget etc ......
I have integrated axel till now; Others are yet to be done.

the project is at
http://code.google.com/p/qtdownloadmanager/