One idea I've borrowed from Everything
is the additional requirement of X number of writeups to achieve a level.
Granted, normalization of a writeup's XP is different, as the goal of 'collecting human knowledge' is to 'answering questions and learning more about Perl', but in both cases experience and levels with funny titles have the dual purposes of recognizing quality contributions to the site and promoting specific behaviors.
The current method appears to reduce rank inflation effectively, for now, without shaking up currently attained ranks. That's a success, in my book. Someday, though, it might be worth considering a dual-nature ranking system.