Better overview:

Who touched what files and when?
git log --name-status
What was my last commit again? I don't see it with git status anymore...
git show --name-status

You can put these and others into shortcuts in your ~/.gitconfig:

[alias]
    co = checkout
    ci = commit
    br = branch
    hist = log --pretty=format:\"%h %ad | %s%d [%an]\" --graph --date=short --name-status
    lg = log --name-status
    p = pull
    f = fetch
[core]
    excludesfile = /Users/you/.gitignore_global
    editor = vim

Inverse .gitignore:

sometimes (as in managing my home directories' config files) i just want to track specific files. Here's the trick:

# ignore everything
*
# add stuff to track
!.vim/
!.bashrc
!some_pattern*
# aand of course...
!.gitignore

Merging

git merge -Xignore-all-space might be helpful sometimes

Misc stuff

These are probably known to most if you use git, but it might be helpful as a primer for some.

Branch related

Create a new branch
git checkout -b <branchName>

If you want to push this to a remote, making it available to others:
git push -u origin <branchName>

Delete local branch
git branch -D bugfix

Delete remote branch
git push origin --delete <branchName>

Config related

Set editor
git config --global core.editor "vim"
(see above for more)