What do you mean by a DMD style multiplier points system thingy? Can you give an example?

I must say I like the idea of changing the karma-style to a more pinball-style kind of thing. Like giving out a pinball score instead of karma points. And showing a Dot Matrix-board alongside each Pinside user (or should I say player?) This way we could also create some nice titles for people with a high pinball score (such as pinball wizard, grand champion and the like).

Speaking of all this, we should probably award users some karma points for posting forum items as well. Hmmmm, I will have a look at this next week...

While this sounds like a great idea, at the moment we're a bit reluctant to implement it, as we fear this will greatly increase the stress on our mail server.

However, there is a solid alternative. You can add all the topics you find interesting / have posts in to you favorites using the 'Add this topic to your favorites'-link at the top of each thread. Now, if you go to your favorites, you can subscribe to its RSS feed. If you use this feed in your favorite mail client or RSS Reader, this gives you basically the same functionality.

Since the favorites-link is not very accessible at the moment we're considering making it a bit more prominent.

It's already there! You can check this over here (second column).