A nice list that will help you to clean up and speed up MAC OS X

From the article:

After Apple recently announced a delay to OS X 10.5 Leopard I had to delay my iMac upgrade until the Autumn. This led me to thinking about how to speed up Tiger to get the most out of my ageing G5.

This is what I came up with:
1. Repair Disk Permissions
Navigate to Applications > Utilities > Disk Utility. Select your Macintosh HD and select Verify Disk Permissions. If needed you can then Repair Disk Permissions.

2. Clear out login items
Its good to check that unwanted programs are not starting up when you login to your Mac. This can be done from System Preferences > Accounts > Login Items.