How do I prevent site scraping?

I have a fairly large music website with a large artist database. I've been noticing other music sites scraping our site's data (I enter dummy Artist names here and there and then do google searches for them).

API/Data Sources - Linking and Pay-Per-Use

I am an independent developer who wanted to write a simple commercial app to display movie showtime information. After doing a whole lot of research, I could not find any good "legal" way of getting this data.

Scrape web pages in real time with Node.js

What's a good was to scrape website content using Node.js. I'd like to build something very, very fast that can execute searches in the style of kayak.com , where one query is dispatched to several different sites, the results scraped, and returned to the client as they become available.