So I added username and node_id tracking as custom variables for my "Better Analytics" add-on (just testing it now on my site... not available for others yet).
For example, you can see the node IDs by visits here (I have it intentionally using the numeric value vs. the string/name since the forum name could change over time if you change the wording or something):
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And then you can also see it broken down by username:
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You can combine the two to see where specific users tend to hang out if you want (you can also break it down by anything really...
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It lets you combine the data with anything Analytics tracks really... Like if you have the demographic/interests stuff enabled for Analytics you can break down the age range of people using certain forums (as an example):
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