Mac: Quick Look is a great way to glance through the text of a document, but the fact you can't select or copy text when using it is kind of a bummer if you're looking to grab a quick quote. If this bugs you, Macworld points to a simple Terminal command that can add the ability.
If you want to select and copy text directly from the Quick Look window, just paste this code into Terminal:
defaults write com.apple.finder QLEnableTextSelection -bool TRUE; killall Finder
This will cause Finder to restart. Once it does, you'll be able to copy and select text out of any text document in Quick Look.