Example global .gitignore file

.gitignore_global

####################################################
# Global .gitignore Flle
# Reference:  http://help.github.com/ignore-files/
# Save this in a file: ~/.gitignore_global
# Then at the command line (you will see more info if a repo is in the current folder):
# git config --global core.excludesfile ~/.gitignore_global
# git config --list
#####################

# Maven #
#########
target/

# Eclipse #  
###########
*.classpath
.settings/

# Compiled source #
###################
*.com
*.class
*.dll
*.exe
*.o
*.so

# Packages #
############
# it's better to unpack these files and commit the raw source
# git has its own built in compression methods
*.7z
*.dmg
*.gz
*.iso
*.jar
*.rar
*.tar
*.zip

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

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

You can use this: https://github.com/github/gitignore

While stuff like .DS_Store* should absolutely be in .gitignore_global, stuff like *.o you might not want in there, since you might forget to .gitignore it for other devs.