Can't get WPA to work in 8.04 (Hardy).
 

I'm at my wit's end here. Tried nm-applet and everything else I can find. Network-manager says "no network devices have been found".

try iwconfig and see if the network wireless device is working

That sounds very much like your (wireless) network card isn't working which usually means your system doesn't have a driver (kernel module) installed for it. If that's the case, "simply" find out what card you have (moreover, what chipset it has), which (Linux-)driver it needs and then get the driver. Some cards don't have a native driver for Linux in which case you may try to use ndiswrapper to "wrap" suitable Windows drivers and see if it helps, but first try to find out if there is a native driver and it's just disabled or needs to be installed separately.

I take it you already checked the Restricted Drivers Manager tool to see if your wireless card was listed (and thus drivers could be installed for) there, right?

Which chip ???. If it's a 3945 it will probably work (to some degree) if you turn WPA off. There is a fix in backports - also an upgrade to Intrepid (8.10) will solve the whole issue.
Anything else, I don't know.