Found this site after reading a CNN article [1] about a NSA tweet [2] designed as a recruitment vehicle. Anyways, take the NSA tweet "tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf." and plug that into quipqiup using the "find spaces" option. Just thought it was cool that there are automated tools to solve problems like this. The site also has a nice help page where you can provide clues.
[1] http://www.cnn.com/2014/05/07/tech/social-media/nsa-coded-tw...
[2] https://twitter.com/NSACareers/status/463321993878994945