Last post in a certain Forum/Category

[lilah]

Hello,
I want to achieve the following:

On the profile page of every member, I want to display the time and date of their last post and also the time and date of their last post in a forum belonging to a certain category (because it's mandatory for them to post in a forum of that category once in a while and I'd like to keep track if they do).

I don't really care to know what that last post was and I don't need a direct link to it, I just want to display when the last post was made.

I hope someone can help me or guide me to a solution.
Thanks so much in advance!