the growth of IJ and other similar-sized LJ-type sites
(I don't know if this kind of thing is interesting to other people, but I certainly find it interesting to look at these numbers and graphs and whatnot.)

There appear to be only 3 LJ-type sites reporting over 100k and under 1M accounts: IJ, DeadJournal, and Dreamwidth (Blurty is slightly over 1M and LJ is over 25M). These 3 sites all report about 450k-650k accounts right now. more interesting, though, is what the graph of number of accounts over the past 8 months or so (since a little before DW's data starts) looks like.
First, note that DJ is essentially flat (they are growing, but at a much slower rate than IJ and DW) and IJ has now far-surpassed DJ to be (probably) the 3rd largest LJ-type site (behind LJ itself and Blurty).
Second, note that IJ's account total is increasing faster over time (concave up) while DW's is increasing slower over time (concave down), and IJ's growth rate (slope) is steeper than DW's throughout the timeframe. It might be that the more people that come to IJ, the greater the general interest in IJ; it might be that DW has somehow begun to saturate its potential market. Also, given how very large a number DW opened with, I have long been suspicious that their initial numbers were not real (perhaps accidentally).