Flying abilities..
Minecraft PC IP: play.cubecraft.net
CubeCraft Games
AquaaXx
Titanic27
For the actual potion from an existing status effect would be jump boost, but thats being added in 1.8 so I'd have to say Haste/ Mining Fatigue. But for the status effect altogether I'd have to say, Shrinking/Growth potions, and splash milk too.
Magma Plays
Shrink/Growth potions in vanilla Minecraft would be awesome! You can get it in a mod if I recall.
Titanic27
With some hard work and some redstone its actually possible in vanilla minecraft
SevereWarning
Hmm, Nausea Pot in Vanilla xD
Magma Plays
Thinknoodles will hate the update with that pot in it. XD (A YouTuber who can't stand the effects of nausea)
SevereWarning
Haha, it's considered one of the best trolling potions.