Illustrator & ruler guides

The multiple artboards in CS4 and CS5 are really fantastic.
No more need to create 20 files for different dimensions and so on. The only drawback is when you use ruler guides, they are on all of your artboards and it is difficult to see what guide you need for a certain situation.

If you want guides to be only on one artboard do the following:

1. Drag your guide to the place you want it
2. Take your scissor tool and click on the guide where you want it to cut.
3 Select the parts you don't want and delete.

Also usefull for other purposes in Illustrator