>とりあえずHomebrew使いたくてうずうずしたので勢いでMongoDB突っ込んだ。

brew install mongodb

mkdir -p ~/Library/LaunchAgents

cp /usr/local/Cellar/mongodb/1.8.2-x86_64/org.mongodb.mongod.plist ~/Library/LaunchAgents/

launchctl load -w ~/Library/LaunchAgents/org.mongodb.mongod.plist