Valve invariably holds a big Steam sale to mark the US Thanksgiving/Black Friday period, and 2014's has just begun. Top deals right now include Watch Dogs, Goat Simulator and The Evil Within.
If you're not familiar with how this works (or simply have enjoyed having money until now), you can check out Alan's guide to getting the most out of the Steam sale . The sale will be going on through until 2 December, so don't feel the need to empty your bank account too early. There will be plenty more to come.