Ideas I've had but don't plan to persue them so ...

[moneyminer]

I'll start it off.

Late service/spot availability alert service. Company name: SX

Imagine this:

Restuarants maintain a database of customers on SX's website.

Someone cancels a booking. Restuarant informs SX. SX sends out an alert via SMS/email that a table is free in 2 hours time to customers that may be interested. They may choose to alert those who have come in at a similar time and day in the past.

Simple yet effective.

This service would prove to be useful to a wide range of businesses for numerous purposes.