Most live CD distros, definitely PCLinuxOS or Knoppix and probably MEPIS, have a program called QtParted which enables you to add, delete and resize partitions. Even if they're not your distros of choice ...
That said, there is an option in the PCLOS "Install" routine to call up a "mandrake-style" partition manager as well with much the same choices.
QtParted is not totally dissimilar to the Windows/DOS program "Partition Magic".
Asus Asus M2N32 WS Pro+Athlon AM2/4200+ â€” GeForce 7600GT â€” 2Gb Cosair VS RAM â€” 500Gb WD5000AAKS SATA Drive â€” PCLinuxOS