Personally, I couldn't care less about Alexa rankings but someone's been asking me about this and I have no idea ...
Apparently AlexaBooster is a "tool" designed to help improve Alexa rankings by simulating traffic to your site - and possible SE rankings as well (though I have no idea how on the 2nd point). Just curious if anyone's used and feedback?
http://www.alexabooster.com/
Looks to me to be using dubious tactics like sending fake hits to your site ...