You may want to look at LVM HOW-TO
LVM allows you to add drives, partitions to a logical volume that groups the disparate pieces together. It's not as bad as you think the installation/config will be. Here
is a good IBM article about LVMs.
Download and install LVM software, do
vgcreate VG_NAME /devwhatever1 /dev/whatever2...
vgdisplay VG_NAME | grep "PE" (to see VGs and verify info)
lvcreate -l VG_NAME -n LV_NAME
mke2fs -j /dev/VG/LV
mount /dev/VG_NAME/LV_NAME /some/dir
Note that this is a distructive process and you will loose all data in the devices you add to the INITIAL
VG. Once in place, you can add a HDD and carve off partitions to add to LV and not loose data already in the LV, you will just have more space.
As a short term fix, you can always do this:
mount /dev/NEWDRIVE /home/myhome/somedir
This isn't very flexibale but will give you space.
You can also make a symlink to another dir in your home dir so if you want to make a partition named /Music, you can do:
ln -s /home/myhome/Music /Music
and your Music dir in your home dir will point to /Music. You will need rights to /Music for it to do any good for you.
Hope that helped and wasn't too confusing...