JM NZB Downloader was designed on these principles
1 - Ease of use
2 - Multiple Connections to the same server
3 - Continuity of downloads after a network disconnection
4 - Decoding of binaries using both yDecode and UUDecode
I think the current version (0.7) is usable. I use it all the time.
Today I released the first Alpha.
The next release will read the size from the nzb file so that the progress bars will work.