Here are some usefull git aliases which i use on a daily basis:
Output samples are generated using clojure repository
List of one line commits
ls = log --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %C(bold blue)<%an>%Creset'
List of commits with changed files
ll = log --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %C(bold blue)<%an>%Creset' --decorate --numstat
List of commits without colors
lnc = log --pretty=format:"%h\\ %s\\ [%cn]"
Commits with dates
ldt = log --all --pretty=format:'%Cred%h%Creset %Cgreen%ad%Creset -%C(yellow)%d%Creset %s %C(bold blue)<%an>%Creset'
Commits with short dates
lds = "!git ldt --date=short"
Commits with relative dates
ldr = "!git ldt --date=relative"
commits with date and times
ldi = "!git ldt --date=iso"
Commit tree
lgraph = log --all --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%ci)%Creset %C(bold blue)<%an>%Creset'
Default look for short git log
ldef = log --oneline --decorate
Commits related to a file
filelog = log -u
fl = log -u
Last commit
lc = "!git ll -1"