I love this topic, Missy!
Here are some of my tips:
M2M the Japanese supermarket on 3rd Ave and 11 Street - cheap good fresh sushi and sashimi, rockin' udon and big selection of veggies very well priced!
Cheap mani/pedis - check out lifebooker.com, then check out the different salons on yelp.com to see what users thought.
Pet vaccinations - if your dog just needs an update on their rabies vaccine or new heartworm meds prescription, check out the schedule at luvmypet.com for the Saturday vaccines at Petco in Union Square and other locations. Its first come first served and the vaccines are half the price of going to the vet. This doesnt include an exam, but it can be handy if your vaccines expire well before your dog's next yearly exam.
Bonus: Nova met his first rabbits while on line for his shot!
Okay, I know Ill think of more...anyone else have some tips to share?