Clearly, cities are chock full of people besides the Hell's Angels, Conan and his homeboys or Count Dracula. A lot of great work has been done in expanding the random encounter possibilities in cities. My favorites include the encounter chart in the front of Judges Guild's Ready Ref Sheets, Uncle Gary's city encounter chart from the 1st edition DMG (home of the original Random Harlot Sub-Table), Midkemia Press's Cities, Matt Finch's City Encounters, and James Mishler's 100 Street Vendors of the City State.
Later non-Advanced editions of D&D expanded the possible encounters by a bit. '81 Expert D&D greatly reduces the chance of encountering undead and adds a possibility of humanoid/demi-human encounters. I like that Pixies and Hill Giants are just as likely to show up as Elves on that chart. The '81 Expert charts also incorporate more human types, particularly the human "monsters" from Moldvay Basic: Traders, Acolytes, Nobles and Veterans. The loss of those entries from the monster sections of later D&D editions was unfortunate in my opinion, but probably another post for another day. The Rules Cyclopedia adds a 1 in 8 chance of being sent to SubTable: 11. City Encounters, which has 160 entries of the butcher, baker, candlestick maker variety. That subchart looks inspired by the Judges Guild chart I mentioned above.
While I like all the expanded post-OD&D options for city encounters, I can't help but feel that there is a lesson to be learned from the simplicity of the OD&D chart. The original version, where the only encounters in cities were undead, name level people, and bands of rowdies, suggests something to me about the original conception of the game terminology "encounter". I think the OD&D version, by omitting encounters like "chamberpot accidentally dumped on you" and "bump into angry muleskinner" and concentrating instead on uber NPCs puts player negotiation and/or the NPC reaction charts front and center. Your party spends a day in the big city and the dice say that something involving a Necromancer goes down. Unless your PCs are already ultimate badasses, they may want to talk their way out of that situation.
Now obviously some things were omitted from OD&D due to simple lack of space, so one shouldn't read too much into something not attested in the text. But plugging the holes in moldy oldy D&D yourself instead of letting later editions do it for you can be a lot of fun. In this case what I find juicy about the stark OD&D charts is that at the end of the day, (assuming everyone makes it out of the encounter alive) some very interesting NPCs will be fast friends, sworn enemies or at least passing acquaintances of the party. That beats the pants off of dealing with pesky beggars, brawling drunkards or hassling city guards, which is how I've seen a lot of city encounters play out.
Also, we went to the big city looking to blow money on ale and wenches and instead we ended up fighting some mummies?!? How cool is that?