A lot of the functionality I aimed to provide has been included in SE proper since then, so most of it I've just let it sit and decay (global search and moderator analytics are the two big ones).
That said, the one app that I've not actively developed (Column 80Column 80), because of its incredible simplicity) but still check every now and again is still getting traffic. Traffic heavilly spiked in June 2010 (due to the contest, fresh entry, etc) but still gets regular monthly traffic of around 100-150 users a month which is about what I would expect for such a niche app.