Hi Alexander,
I would say the Links module is easy to understand as it is very simple but has both a Module control Links.ascx and an edit page LinksEdit.aspx, Blog and Forums are a little more complex as they have view pages in addition to an edit page so you may also want to refer to them for examples.
Just keep in mind that the whole module architecture is going to change to WebParts so anything you build now will have to be converted later. It may not be that difficult to convert but then again it may be, I'll let you know after I convert some of the current ones
Anything to help xsp2 along is great!
Cheers,
Joe