This is my best case .gitignore file.

master-git-ignore

# Services #
############
*.sassc
.sass-cache

# Generic #
###########
/log/*
/tmp/*
/pids/*

# Rails #
#########
*.rbc
capybara-*.html
.rspec
/.bundle
/vendor/bundle
/public/system/*
/coverage/
/spec/tmp/*
**.orig
rerun.txt

# Edits/Editors #
#################
._*
*~
*BAK
.project

# OS generated files #
######################
.DS_Store?
ehthumbs.db
Icon?
Thumbs.db
.AppleDouble

# Logs and databases #
######################
*.log
*.sql
*.sqlite
*.rdb

# Other Code Management #
#########################
.svn

# Sphinx #
##########
*.sphinx.conf
/db/sphinx/*

# Cache #
#########
*.cache

# NPM #
#######
node_modules