I'm looking for a simple way to identify the top contributors (content created by or modified by) across my entire site collection. This is strictly for my own use as an adoption tool (think "user of the month") so I don't need an elegant presentation, just the data. Suggestions?
You can enable usage processing in Central administration then turn on auditing in the site collection. The data can be a bit of a bear to work with, but the reports you can create are flexible enough that you could retrieve some of that data. There are other third party tools that will give you a better grasp on usage and content better if you're looking for a long term solution.
It would be pretty "expensive", but you could use a Data View Web Part (DVWP) with DataSourceMode="CrossList" to count items per user. Since if sounds like you'd run it infrequently, the "expense" might not matter.
The good thing about this approach is that you'd have a lot of control over what you got.