Mini-computers that fit in the palm of the hand are fast taking over from traditional paper organisers such as the Filofax, says one expert.
The hand-held machines not only allowed people to arrange their busy lives but can also connect to the Internet, send and receive e-mails and even be used as mobile phones.
Their growing popularity in recent years has added to pressure on manufacturers of paper organisers such as Filofax, which confirmed that it hoped to relaunch the brand by getting rid of the 1980s yuppie image.
The company changed hands for the third time in three years last July when it was bought by Scottish diary company Letts.
The past four years has seen a huge rise in demand for handheld computers, otherwise known as Personal Digital Assistants (PDA) or palmtops, according to Tom Dunmore, deputy editor of leading technology and gadget magazine Stuff.
"They are now even more powerful than a desk-top computer yet they fit in your hand," he said.
"You can use them to store your addresses and diary details and transfer all that information to another computer. If you lose the hand-held computer you haven't lost all that information, unlike with something like a Filofax."
The current best-selling models on the market are from a computer called Palm - its cheapest machine, with a black and white screen, starts at €160.
Top-of-the range PDAs can cost up to €977 and use Microsoft computer software.
"You can pick up a Palm for €160, so when you consider you pay €80 for a decent Filofax, it is not that much more expensive," said Mr Dunmore.