Sorry, I can't say I know of any specific meetup groups of Leaf fans. However, if there should ever be a gathering of people from this site for a game, I'll do my darndest to attend, although with two young kids it's often hard to find a good day to work it out.
As an aside, good for you for hanging in there with the Leafs, scottishguy. I was afraid the horrible end to last season would have killed your great enthusiasm for the team. Good on you for coming right back for more. Cheers!