Onwards with the theme, and we'll have ourselves a lovely Sudoku variant. The rules are as follows: 1-8 go into each row/column/box, with two 2's in each. Moreover, the cells containing the 2's are disjoint (so don't touch at either an edge or a vertex). Think Sudoku crossed with Star Battle then.
I am quite pleased with how this one turned out, given that I started this on something of a whim. Enjoy!
EDIT (14:18, 2/3/2012): fixing non-uniqueness.
see comment from rob):