Since it really belongs over here, one of the projects I am working on is a Mutants & Masterminds MUX, set in an original world. The general idea is that the city is frikken huge, not like Mega-City 1 from Judge Dread huge, but huge enough that it goes from horizon to horizon.
Because it's so big, there's so many people, that even thousands of heroes can't stop all the crime everywhere (I am taking that from Dread though) so there is always a need for heroes even though there's tons of them.
I want to have different areas of the grid be set up for different styles of play, some will be grit and gritty for vigilante type characters where it's messy and bloody, some will be more akin to four color good guys vs bad, some will be in between. This way there is a wide variety of areas for people to play in and a wide variety of acceptable characters.
Starting characters will be of two varieties, standard Power Level 10 characters will require an approval before play, while anyone can make a quicky character that is PL 5. PL 5 characters are more 'High School' or 'Side Kick' type of characters, or just someone very very new to their abilities. PL 5 characters won't require an approval, just go through the chargen and if they finish to the code's satisfaction, they can play immediately.
Obviously I can't run it all by myself, and there is some huge gaps in themes, so when I am ready I am going to look for other staffers but until then, that's the general idea.
I went with Mutants & Masterminds because the system is fast and simple and generally should be pretty smooth for combat scenes I am hoping without to much chart checking, and chargen is a breeze compared to, say, Hero System.