JumpFuck

From Esolang

Brainfuck, but with some differences:

Unbounded cell size. (already done by many BF interpreters)
Automatically expanding tape. (ditto)
An extra block of memory (also automatically expanding) containing jump points.
Two extra commands:

&    Replace the jump point whose ID is in the current cell with the current jump point, and
     change the current cell to 0 if we come from & or the argument if we come from %.

%    Jump to the point whose ID is in the current cell, using the next cell as an argument.

This makes it far easier to compile to.