When I installed SL4.0 it created one logical volume for / which is not
suitable for a production environment. Instead of reinstalling I
wanted to try to resize the volume so I could create new volumes in
the volume group instead. The main issue I ran into was that resize2fs
is not in e2fsprogs-1.35-11.6.EL4 (its in e2fsprogs-1.32-15.1 on my
3.x machines). Don't know why.

Steps to follow (I resized / to 8G):

BACKUP!
download and build http://e2fsprogs.sourceforge.net/
boot from cdrom to rescue mode (choose not to mount)
lvm vgchange -ay
mount /dev/VolGroup00/.. /somewhere
copy the resize2fs binary from /somewhere
unmount /somewhere
e2fsck -f -v /dev/VolGroup00/..
resize2fs /dev/VolGroup00/.. 8G
lvm lvreduce -L 8G /dev/VolGroup00/..
e2fsck -f -v /dev/VolGroup00/.. (to be sure)

Done, now you can create volumes with lvcreate.

Joakim