Sometimes, when you want someone else to look at your blog but not see posts belonging to one category. Try the following link to my blog index for instance: George Files without Ads or Friends. You should see my index page without posts that belong to the Ads or Friends category. This is rather useful if you want people to just see certain posts of your blog and you have lots of categories. Just put it as a space separated list in the cat variable.
Here’s an example of a link:
The %20 is a space, and the numbers 37 and 29 are the category ids for the categories that I don’t want to include. If you use the numbers without the – sign in front of them only those categories will be displayed.