5 best free web apps: 3. Doodle

Simple but effective is the key with our third online web app Doodle. Most people I know through work have used this app, so chances are that if you're in the tech space you will have too. If not, you may surprised at just how simple it is.

Do you remember the last time you tried to get your mates together in the pub? All of them, on the same day? It can be difficult to juggle emails, suggesting a date only to find that John can't make it, while trying to remember that Susan can't do Wednesdays.

Well this is exactly the problem that Doodle solves! Using Doodle feels like simplicity itself. Enter your dates, receive a link, share with your friends and wait for them to enter their availability. Then you can easily see the count of who is free on which night (and a grid of exactly who, if some friends carry more weight than others).

It somehow seems counter-intuitive that a business can make made from such a simple idea, but personally I think it's an important lesson for any startup. Simplicity is key.

Starting with paid-for Premium Doodle to capitalise on people who want a bit more from the service, Doodle have now launched BookMe as a complete service for time-based service industries such as hairdressers. Given their reputation, it deserves to be a success.