My last one for this year, I think
http://www.cokeandcode.com/fourkay/shuffle/
Drag the coloured blocks to slide them round the level. When two blocks of the same colour touch they will join and can then only be moved together. Move the coloured blocks to the matching coloured targets (dashed boxes) to complete the level.
All the details are on the page. You get a yellow box for completing the level and a green one for getting it done on target moves. The given targets are what I’ve (and others) have done them in - there may still be better solutions available (if you find one, please post a screenshot).
Still a work in progress (though all 16 levels are available now). Any bugs or issues reported much appreciated. No room left for new features, but I think I might try to write a bigger version after the contest.
Kev