Lists are really useful for finding others around a specific topic. http://listorious.com/ is a good place to find ones already created and there’s ones for top egovernment people, government bodies etc.
Here’s one I’ve created which I grew through following links to others lists in this area http://listorious.com/pauloCanning/pubsecpeeps . Here you can see some created around the ‘government’ theme http://listorious.com/tags/government
I haven’t analysed this but I’ve noticed that from following my list others have added people to their following and hence made connections which they might not otherwise have made.