Achivements & Reputation

Some day (cue wistful music and sepia tones), I'd like to implement an achievement system, like you find in MMORPGs:

I'm actually quite surprised that there aren't any, as far as I know, roguelikes with an achievement system. Though you could argue that the game score is a measure of achievement in itself.

Further to that, I'd like to implement factions & reputation (with faction quartermasters):

Of course, you could argue that the deities in Crawl are effectively factions.

What can Roguelike Developers learn from MMORPGs?

My original post on the relationship between MMORPGs and Roguelikes seems to have caused a bit of a stir, judging by some of the comments. I've clarified my thoughts in the comments there. Meanwhile, I'd like to ask a few follow-up questions on the subject:

1. What can Roguelike Developers learn from MMORPGs?

2. Are there any features in an MMORPG that should (or could) be implemented in Roguelikes?

Or alternatively:

3. Are there any features from Roguelikes that would work well in an MMORPG?

There are a few features in MMORPGs that I'm considering adding to the (ever-expanding) todo list for Kharne once I restart development, but in the meantime I'd like to hear your thoughts on what you'd like to see in Roguelikes in general (not just Kharne).