Oh boy, I have a bunch, depending on how you count...
At home/school, in use:
15 gallon, houses guppies, glowlight danios, and ghost shrimp
10 gallon, split to house my HMDTPK and SeDT
5 gallon, houses my HM Dumbo
5 gallon, houses my CT(?) female
2.5 gallon, hospital tank that currently houses the previously mentioned HMDTPK
At home, not in use:
5 gallon Fluval Chi, may eventually house the HMDTPK
30 gallon tall, doesn't hold water, used as a herp tank
40 gallon breeder, drilled (doesn't hold water) herp tank
At home, in use:
Not-technically-a-tank 6'Lx2"Wx4xT wooden/glass/wire cage, houses my 7' long Argentine Boa Constrictor
5 gallon, houses a CT male
It's funnier in Enochian.