Something

root@coolzero-ubuntu:~# ls -l /usr/src/*
/usr/src/linux-headers-2.6.15-26:
total 116
drwxr-xr-x 26 root root  4096 2006-08-28 22:58 arch
drwxr-xr-x  2 root root  4096 2006-08-28 22:58 block
drwxr-xr-x  4 root root  4096 2006-08-28 22:58 cluster
drwxr-xr-x  2 root root  4096 2006-08-28 22:58 crypto
drwxr-xr-x 53 root root  4096 2006-08-28 22:58 drivers
drwxr-xr-x 66 root root  4096 2006-08-28 22:58 fs
drwxr-xr-x 44 root root  4096 2006-08-28 22:58 include
drwxr-xr-x  2 root root  4096 2006-08-28 22:58 init
drwxr-xr-x  2 root root  4096 2006-08-28 22:58 ipc
drwxr-xr-x  4 root root  4096 2006-08-28 22:58 kernel
drwxr-xr-x  5 root root  4096 2006-08-28 22:58 lib
-rw-r--r--  1 root root    13 2006-08-03 07:08 linux-headers.revision
-rw-r--r--  1 root root 43865 2006-05-18 16:41 Makefile
drwxr-xr-x  2 root root  4096 2006-08-28 22:58 mm
drwxr-xr-x 36 root root  4096 2006-08-28 22:58 net
drwxr-xr-x  9 root root  4096 2006-08-28 22:58 scripts
drwxr-xr-x  4 root root  4096 2006-08-28 22:58 security
drwxr-xr-x 17 root root  4096 2006-08-28 22:58 sound
drwxr-xr-x  2 root root  4096 2006-08-28 22:58 usr

/usr/src/linux-headers-2.6.15-26-386:
total 320
lrwxrwxrwx 1 root root     31 2006-08-28 22:58 arch -> ../linux-headers-2.6.15-26/arch
lrwxrwxrwx 1 root root     32 2006-08-28 22:58 block -> ../linux-headers-2.6.15-26/block
lrwxrwxrwx 1 root root     34 2006-08-28 22:58 cluster -> ../linux-headers-2.6.15-26/cluster
lrwxrwxrwx 1 root root     33 2006-08-28 22:58 crypto -> ../linux-headers-2.6.15-26/crypto
lrwxrwxrwx 1 root root     34 2006-08-28 22:58 drivers -> ../linux-headers-2.6.15-26/drivers
lrwxrwxrwx 1 root root     29 2006-08-28 22:58 fs -> ../linux-headers-2.6.15-26/fs
drwxr-xr-x 4 root root   4096 2006-08-28 22:58 include
lrwxrwxrwx 1 root root     31 2006-08-28 22:58 init -> ../linux-headers-2.6.15-26/init
lrwxrwxrwx 1 root root     30 2006-08-28 22:58 ipc -> ../linux-headers-2.6.15-26/ipc
lrwxrwxrwx 1 root root     33 2006-08-28 22:58 kernel -> ../linux-headers-2.6.15-26/kernel
lrwxrwxrwx 1 root root     30 2006-08-28 22:58 lib -> ../linux-headers-2.6.15-26/lib
-rw-r--r-- 1 root root  43860 2006-08-03 07:09 Makefile
lrwxrwxrwx 1 root root     29 2006-08-28 22:58 mm -> ../linux-headers-2.6.15-26/mm
-rw-r--r-- 1 root root 266735 2006-08-03 05:08 Module.symvers
lrwxrwxrwx 1 root root     30 2006-08-28 22:58 net -> ../linux-headers-2.6.15-26/net
drwxr-xr-x 9 root root   4096 2006-08-28 22:58 scripts
lrwxrwxrwx 1 root root     35 2006-08-28 22:58 security -> ../linux-headers-2.6.15-26/security
lrwxrwxrwx 1 root root     32 2006-08-28 22:58 sound -> ../linux-headers-2.6.15-26/sound
lrwxrwxrwx 1 root root     30 2006-08-28 22:58 usr -> ../linux-headers-2.6.15-26/usr