HAID  One of those great little single purpose utilities.

At work, the Microsoft ISA proxy server array would

cause lots of username/password challenges just to browse the internet. Other apps like SoftwareUpdate, Eclipse patching, and iTunes just failed.

TinySvr fixed all of this for me; it authenticates

with the corporate proxy server using my credentials. The network security guys are OK with it as it is only accessable to apps on the "localhost" (assuming you have the OSX firewall ON).

I've noticed that some network passwords don't seem to work. If I change the password to one with characters, numbers, dash, underscore, etc; then TinySvr works quite well.

TinySvr is highly recommended.  
(Version 2.2)