Minor UI grumble: When you're editing your site switcher list the "More Stack Exchange communities" seems like unnecessary UI clutter.
Yes, I know one of them has a big "ADD" button next to it. Didn't stop me from using the wrong one.
I may be a blind idiot, but years of experience have taught me that's a good assumption about all users :)
I'd like to propose two possible changes to make it a little nicer:
1 - Hide the "More Stack Exchange Communities" list when editing the switcher list.
Quick and dirty fix with a little CSS & JS toggling
2 - use the "More Stack Exchange Communities" list for the editing
+ buttons in the More Stack Exchange Communities list, and
x buttons in the Your Communities list when you hit edit. (You could even show the
+ button all the time - this would make adding communities to the switcher easier: Just Search & Click)
I like (2) myself even though it's probably more work to implement.