Here is a message queue example which we use. There is a need keep the reporting load off the day time production window where on-line has the priority.

A user requests a long running report during the day. The request is captured in a web app and results in the encoded request being stored in a message queue on a SQLServer. At 0100h an sp is fired up by a scheduler, reads the requests in the queue and executes the long running reports/extracts etc. All finished by 0800h and the users download their output from the website. This way we don't have to write polling sp's to look in a "to-be-actioned" table

(BTW the example in this thread was very interesting but didnt work as coded! Not sure why but comparing the code Dave Pinal's published technique, the deltas were in the mmessage type and contract options. (Not got time to get the bottom of it but many thanks for sparking up the interest. Article much appreciated)