sneaksms.com

From U.K,

For all your funnies, go to www.sneaksms.com

the recipient will never know it was you, just imagine sending it and sitting next to the recipient and watching their reaction, quality!!

From Bristol,

Have a look at http://www.pretendafriend.co.uk

Allows you to send SMS to yourself pretending to be some one else.
You can time delay the messages so it can be set up to deliver when you want in front of the people you want to use it against.

Can send online or submit a text request as well.

Good for excuses 'Thanks for staying late last night: "The boss"
Reminders "Get you mum a card on the way home"
Pranks "Who is that standing next to you they are cute" "Blondie"