Thanks daredevil123 for the recos.
For starters may go in for a wide angle to complement the 18-135mm (which is good lens too), just a little itchy to have more zoom.
PC lens would probably end up last on my shopping list. (zerocoolAstra thanks for the clarification) I was lost with the jargon too ;p
Is there a big difference in using non Canon lenses? I seen some really good lenses from Sigma, Tamron & Tokina but never used them. Stuck with Canon and Nikon (on the older camers) so far.