There is an awesome gift with purchase (GWP) available from Butter London on right now! I got the information from Body and Soul's Blog (An Awesome blog, go take a look at her swatches!).
The colour that comes with a $25 USD purchase or more is Racing Green a colour that looks so lovely and rich! I've not tried the Butter London range myself, but I've heard good things about it. Plus the bottles are so cute! If you're interested in trying the range and like green polishes (like me!) now would be a great time to try some out! No More Waity Kaity is also available from them at the moment, the one based off the English Royalty Wedding that's such a hot gossip topic at the moment!
The code is StPaddyDay11