Microsoft is offering commuters in London's Zone 1 and 2 free travel to promote its new Office 2007 application.
The promotion, which is running until 8 May includes 20 branded taxi's with the software's logo.
However before you starting thinking they will come in handy on a trip back from the pub on a school night, the Taxi's will only be available between 7:30am and 9:30am.
The taxi rides must be confined to Zones 1 and 2 and riders will get a postcard offering a free trial of the software.
"As the weather gets hotter and the tube more unbearable, we are helping London's workers have a better day by laying on free cabs to keep them fresh in body and mind", said Darren Strange, UK product manager for Microsoft Office 2007.
"Office 2007 is all about helping workers do their job better and, by allowing them to get a free taxi to work, we hope this will help them too."