You don't have to be chained to Monaco if you don't like it. I changed it to Inconsolata, which is as simply as downloading it (click on the Open Type File link).
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Once you click on the downloaded file, the Font Book app should open up automatically, showing the font face and with a Install button.
Once you do this (I love this part) any open font selection windows will refresh automatically, and you can pick this new font for your terminal (which, by the way, I hope is iTerm because ... if not, why?)