How can a drive appear full when its not. I've reformatted but still can't use all of it.

cp: writing `/mnt/usbdrive/enine/Pictures/2005 Aniversery/im002591-800x600.jpg': No space left on device
root@darkstar:/home/enine# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda1 9381028 7467780 1412828 85% /
/dev/hda4 93232360 78665180 9831220 89% /home
/dev/sdc1 57685532 32232976 22522304 59% /mnt/usbdrive

how much data are you trying to move. Looks like you've got about 2 gigs available. The cp command probably writes it to a temp file first, then to permanent storage, so it needs to use twice as much space as the amount of data you're writing.

just a bunch of little 4m pictures

Maybe you're running out of inodes?

Try:
df -i

Whats your permissions?
mount | grep -i usbdrive

Make sure your not mounting a directory with data in it. Common mistake.

Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sdb1 7325696 52729 7272967 1% /mnt/usbdrive

looks like I'm only using 1% of my inodes on it? Or does that mean only 1% is free?

hmm, df -T says its ext2 instead of ext3, maybe thats the difference, I can't recall the ext2 limits now.

How many is a bunch and how are they organized? FAT has a terrible and not-well-documented limit for files/directories on the root of a partition. The limit is 512 if all files are named in 8.3 format. When using long names, though, every 13 characters consumes another file entry. EG: Your filename from the first post, 16 characters long, needs the same number of file entries as two files that are only 11 characters each.

This limit only affects the root of a partition. It's annoying but easily worked around by organizing files into subdirectories. I personally think there should be a warning on usb disk packages because I see this a lot.

Thousands, but they are in subfolders. About 10G worth now as I have pictures going back to 2000 then a few scanned from earlier years.
The external drive is formatted ext2. Well was I formatted again last night and switched to ext3.

Still having problems, or did you solve it?