last post by member

It would be cool if, in a member's profile, it indicated when their last post was, or when they were last 'active'.

Kinda handy to judge whether a person comes online very often. If they've not been around for 2 months then a PM might be waste of time!

I don't think it's particularly invasive; besides you can infer this information anyway by doing a 'search for posts by member' and seeing when the last one was, which is just a little more tedious.