So vines are like ropes.. How about:
Vines that can be used to lasso animals / mobs.
A stationary block that turns with thorny vines waving out that damage mobs / players. (needs to be powered?)
Pegglefrank's little vine on that stump makes me think of SMB Flower fireball shooters, or a little shop of horrors plant that can eat you then teleport you to Vinealandia. A place where everything is giant sized vines and flowers with sky above and void below.
Giant vine 'trees' that can be hollowed out and lived in.
Animated vine 'legs' that raise you up and make you walk faster, but have to have water, or can't work, so only work for moving faster on water.
Vine bridge guns. Load vines into a compressed air gun, and shoot across a chasm or valley and then it creates a (temporary?) bridge across. Need to have as many vines in the gun as blocks distance between where you are and the destination.
Vine mats that slow movement, like soul sand. Easier to defend against approaching mobs.
Just a few ideas. Good luck with the mod!