A customer's server has run out of inodes, but has a tiny amount of files:

mailserver 3# find /usr | wc -l
   112200
mailserver 4# df -i /usr
Filesystem  1K-blocks      Used     Avail Capacity  iused    ifree  %iused 
/dev/raid2a 153018716  17104340 128263444    11%  9539859    17131    99%

That's nearly 100 times as many inodes as files/directories! Now, I know 
an inode != file/directory, but it should be the same order of magnitude!

Compared to a server here:
ugly 421# find /usr | wc -l
  1434411
ugly 422# df -i /usr
Filesystem  1K-blocks     Used     Avail Capacity  iused    ifree  %iused 
/dev/raid2a 241151544 134683608  94410356    58%  1416711 13621495     9%

What's going on on our customer's server? What tools can I run (in 
multi-user mode) to track this down a bit more?

-- 
Stephen