Is called "The oldest one" in the pictures
and it was one of the first T-Flip Flops used.

it uses atleast:

2 pistons (not sticky)
3 redstone torches
2 redstone dust
3 solid blocks

this means:

8 cobblestone
2 iron
6 woodenplanks
3 sticks
7 redstone
and 3 solid blocks

and is 5x1x4 = 20 blocks big

Is called "The one from WooltecMC" in the pictures
and is stackable and the

it uses atleast:

2 sticky pistons
1 redstone repeater
1 redstone block
1 solid block

this means:

2 slimeballs
8 cobblestone
2 iron
6 woodenplanks
2 sticks
3 smooth stone
14 redstone
and 1 solid block

and is 7x1x2 = 14 blocks big

video:
http://www.youtube.com/watch?v=TGSU-57DJFs

Is called " The one i learned from a friend" in the pictures
and is stackable and the most compact (12)(6x1x2) from them all

it uses atleast:

2 sticky pistons
1 redstone torch
2 redstone block
1 solid block

this means:
2 slimeballs
8 cobblestone
2 iron
6 woodenplanks
1 sticks
21 redstone
and 1 solid block

and is 6x1x2 = 12 blocks big

Is called "The one i learned from mcKrawll" in the pictures
and is the most valuable of them all (because you need to go to the nether) and also the biggest (30) (5x3x2)

it uses atleast:

1 sticky piston
1 redstone torch/lever
1 redstone block
2 solid blocks
1 redstone comperator
1 redstone repeater
2 redstone dust

this means:
1 slimeballs
4 cobblestone
1 iron
3 woodenplanks
6 sticks
19 redstone dust
1 nether Quartz
and 2 solid blocks

and is 5x3x2 = 30 blocks big

video:
http://www.youtube.com/watch?v=2pfh826t88I