It'd be nice if, once you'd been somewhere, it made a note of which vendor lived in that place on the map. Give some additional value to exploration, as well as helping out the easily turned about.
I agree with this one! I have completely forgotten where the vendors are! You could extend this to allow people to just make their own notes, give them a travel diary option so that they could free write notes about places as reminders.
I'd also like to see things you've "learned" show up on the map: vendors, my own house, teleport home. A balance that doesn't get us into jamming a whole lot of text on the screen cluttering things up would be nice too.
Maybe some sort of system of cartography symbols used could make it fun and informative (and something quickly discoverable by players).