(see CategoryHowTo for a list of all HOWTO pages)
Usage models:
WorkingPractices describing several ways to use Mercurial
How to handle MultipleCommitters
CommunicatingChanges describes the various ways Mercurial can exchange changesets
How SymbolicLinks work
Setup and Automation:
PublishingRepositories and ServerInstall describes various ways to make your code visible to the world
MercurialOnSourceforge explains how to serve Mercurial repositories using Sourceforge.
Features:
NamedBranches gives an introduction to this feature
See also: FAQ, TipsAndTricks