At any given time, I am watching about 35 different security related RSS feeds. While there are a cornucopia of RSS feed readers to choose from, if you have an iPad (or if you dont, this could help you make up your mind to get one), Early Edition is one that is definitely worth giving a looksee. As you can see by the graphic, it aggregates all the RSS feeds that you watching and presents it to you in a newspaper like format.
The user interface has really been thought out with this iPad app. Each days RSS feeds are kept in a seperate file so that you can go back over several days to see what is doing on. If you skip a day with looking at the feeds, it will lump all the days to together into one file so you will have a little more to go over. One of the features that I have found handy is that you can gauge to a degree how significant a particular entry is by looking at how many of your other RSS feeds that the same information comes from.
As to what RSS feeds to watch, that is a decision that you will need to make. The list I use changes over time as different feeds come and go. One type of feed that I like to watch is those that are available from the different AV vendors. When you start seeing a particular virus, it is nice to know how soon your particular vendor (or potential vendors if you are looking to make a change) has an update available and whether or not you may need to apply a special patch or update to be protected until the permanent fix/update is available for deployment.