Skype to SMS
The trickier part was getting it so a cellphone could send an SMS text message to a Skype user, but Connectotel has also worked it out so you can do the reverse, too (yeah, it's already fairly easy to send an SMS from a PC). Basically you just add "smsgateway" to your user list, type in the number of the person you want to bother, and then enter you message and you're good to go.