Since this appears to be in fashion, I thought I'd share a few mercurial tips of my own.

qstatus

I created a hg qstatus command by adding the following to my hgrc:

[extensions]
parentrevspec =

[alias]
qstatus = status --rev qtip^:qtip

This shows the files modified by your topmost mq patch.

I often switch to a patch and then run

$ vim `hg qst -n`

to open all the files touched by that patch.

Indexing into your patch queue

Passing -v to hg qseries shows you which patches in your series are applied and gives a zero-based index for each patch in your queue. For instance,

$ hg qseries -v
0 A foo
1 U bar
2 U baz

This is particularly useful because mq operations can take these indices as operands, as in

$ hg qgoto 2
applying bar
applying baz
now at: baz

You can make -v the default for qseries and qapplied by adding this to your hgrc:

[defaults]
qseries = -v
qapplied = -v

I like combining this with hg-prompt; there's now a patch|topindex command in hg-prompt which corresponds to the index of the topmost applied patch in your queue. (It's in the main repository, but the docs aren't yet updated.)