A quick request of everyone who writes web pages, especially weblogs, or who designs web page templates:
Give every heading an id, so that other folks (and you) can link to sections of an article or entry.
It's not quite Purple Numbers but it does the job more than effectively (and it's not half as overkilly). I reckon it's fair to assume that if someone wants to link to a part of your page in another page, they'll have the ability to view your page's source and find the ids. And if they can't, purple numbers would probably befuddle them anyway.
I do it automatically - it really takes little effort. Another point is to use proper titles, not #title4, so that if you add a chunk, nothing will break (and referring urls look much friendlier).