I feel at a loss often as to whether pick a specific tag, or a generic one (is it #games or #gaming? Is it #politics or #elections?), and even more so when I don't even know what single tag is the most appropriate one... it's rather limiting and reduces discoverability of content?
for example, nobody subscribed to #music alone will see anything in #dubstep, nor will people subscribed to only #dubstep see #triphop...
allowing us to tag things in multiple ways would allow for far denser interlinking.