Scorpion toxins have been a popular subject for Foldit puzzles. They tend to fold into structures with many disulfide bridges, three beta sheets, and an alpha helix. The wikipedia article scorpion toxin is a good place for examples.
Three different scorpion toxins are regularly seen as revisiting puzzles. See Revisiting Puzzle: Scorpion Toxin for details.
A classic of Foldit!
New player puzzle[]
The toxin in the early Foldit puzzle seen here is from Pandinus imperator, and has only 35 residues with the sequence:
tisctnpkqcyphckketgypnakcmnrkckcfgr
It is shorter than the usual three-sheet toxins.
This sequence is found in the PDB as 2PTA.
The protein can have three disulfide bridges, at 7-28, 13-33, and 17-35.
This protein was last seen in New Player Puzzle 2: Scorpion Toxin in 2011.