I recently bought (via eBay) a USB data cable for my LG CU400 cellphone. Sadly, I did so before realizing that LG apparently doesn't provide software besides basic Windows drivers for this phone. (For those interested, I used the drivers from a package named LGUSBModemDriver_Eng_Ver_4.5.exe, found with a Google site search.) At any rate, my investment thus far (which was only about $7, truth be told) was looking like a poor one.
But tonight I tried BitPim even though my phone model is not listed as explicitly supported. To my great surprise, BitPim recognized my phone as an "Other CDMA phone". That meant I got filesystem-explorer-type access, but none of the other GUI goodies. That's okay, though -- it only took a little bit of poking around to figure out where the phone keeps my photos, videos, mp3s, and so on.
And best of all, I was able to pull off the hack described here. So now I can use the mobile versions of Google Maps and Gmail on my phone without answering a network usage permission prompt for what seemed before like every packet transmitted!
12/21/2007 Followup: I forgot to note that I was doing all this on a Windows 2000 machine. But I'm pretty sure the drivers I got were rated for Windows XP, too. No clue about Vista support for any of this stuff.