increasing partition sizes

I am running low on space under /var and /opt. I have been using softlinks pointing to a large partition, and until now this has worked well enough. However, and latest ZCM update is giving me problems, and it needs more space in /var and /opt. most of the server disk space is ext3 and managed by LVM. We do have a 30 GB NSS volume, but I might ditch that if needed.

What is the best approach to reallocating more disk space? Thanks, Chris.