Top places/things to see:

Cornerhouse
A great independent cinema that's dead cheap.
70 Oxford Street, Manchester, M1 5NH
www.cornerhouse.org

Museum of Science and Industry
Liverpool Road, Castlefield, M3 4FP
www.mosi.org.uk

China Town
It's the only place I could find Mountain Dew in the UK hidden amongst all types of peculiar Chinese snacks. You can get cans for 60p... Bargain!
George Street, M1

Central Skate Park
A small warehouse converted into a great small setup. The street course ticks every box in my books but can get insanely busy, so pick your time wisely.
28 Mason Street, M4 5FT
www.centralskatepark.co.uk