Transit
Metro Transit deserves major kudos for its New Year's Eve service, which is completely free after 8:30pm and has extended hours, with some buses running as late as 2:30am. The ferry continues to run every half-hour well past midnight; the last boat leaves Dartmouth at 1:30am, then departs back to Dartmouth from Halifax at 1:45am. Alternatively, Dartmouthians partying up on Argyle or wherever can catch the last boat leaving the Halifax terminal at 1:45am. Check the complete schedule via thecoast.ca/NYEbus.
Taxis
There are no taxi zones in place in Halifax, but it doesn't matter; like most cities, it's a problem catching cabs in Halifax on New Year's Eve because there are simply too many potential customers for the number of cabs available. It makes no sense to operate and insure a cab that only runs one night a year.
In a previous life, I drove a cab for five years, so I'm going to tell you the one and only sure-fire way to secure a cab driver for New Year's Eve: Bribe him. It's illegal, unethical and costs a lot of money, but that's how you do it. Take a cab somewhere today and make a deal with a driver---give him $50 above your fare and tell him there's another $100 in it for him if he picks you up at a set place and time on New Year's Eve.
Don't even attempt to get fancy with New Year's cellphone calls and such---exact place, exact time, only, and make sure you're there. Otherwise, you can play cab roulette with the thousands of other folks trying to flag down cabs. --Tim Bousquet