I'm sure everyone is aware of the Steam sale, but I found even better deals at
www.gamesplanet.com
DOOM and Fallout 4 are both £12.99 ($16 USD) instead of $20 USD on Steam. There may be other good deals but those are the ones I was interested in.
On top of that you can
join their steam group for an extra 5% off. You have to attach your steam account to their store account