Now it is possible have subscriptions on feeds for specific tags (categories) 
Here are some examples:
| Navision Feed | http://techblog.byllemos.com/?feed=rss2&tag=navision |
| OS Feed | http://techblog.byllemos.com/?feed=rss2&tag=Operating-Systems |
If you want a feed to a tag, which is not mentioned – then simply construct it your self.
The syntax is:
http://techblog.byllemos.com/?feed=rss2&tag=input_tag_here
It is all so possible to have feeds directly on categories. But here you should know the category number.
The syntax is:
http://techblog.byllemos.com/?feed=rss2&cat=input_catno_here