I love learning new Kanji, probably too much in fact. Once I finished Remembering The Kanji Volume 1 & 3 I couldn't just quit! I had to find more characters to study! After memorizing another meager 25 or so Kanji to catch up to the proposed revision of the 常用漢字 standard, I tried to find good frequency lists on the internet but none were very extensive and had relatively limited sample sizes.
At some point, an idea came to me that the Japanese Wikipedia would be a really good source of data. It could be downloaded for offline processing and obviously includes every possible topic. I whipped up a couple of Perl scripts to process the 20 gigabytes or so of data. About six hours later (maybe I should have done this in C++?) I had a nice sorted table of characters ready for processing. I wrote a couple more scripts to generate reports that applied the frequency data to the RTK1, RTK3, 常用漢字 (old and new), and finally the 人名用漢字 (just for fun) character lists.
After I completed by analysis of Wikipedia, I ran a slightly modified version of my script on a several gigabytes of assorted novels in raw text format. I'm also including this data as it is another great indicator of actual Japanese language usage. Depending on what kind of text you are planning on reading, this report may even be more suitable than the original Wikipedia analysis.
These reports span over 500 million characters, (over 20k of which are unique). This is obviously a tremendous amount of data. Let me know if you want to see something else included in the reports about this data that isn't yet!