Best Steam Background

Lina and Crystal Maiden

This

Gordon & Alyx

Haven't seen them all, but the one I'm using right now is really good and really cheap.

Atlas and P-Body

I like the FTL Title Screen one. It is what I am using.

I really like this CSGO one.

Maiden and Lina :D

I really like the silly don't starve backgrounds :D

Trine 2 backgrounds are beatiful. I use "Cave" one.

Really Big Sky's Engine, 1.. 2.. 3.. KICK IT!'s Ancient Technology, Sanctum 2's all of them

The one I'm currently using.

Possibly the dreaded Deerclops.

The one I have

Mine is also the one I'm currently using
http://steamcommunity.com/market/listings/753/Guarded

Tower from Trine 2

I've been using an FTL one that I rather like, but there are so many coming out so frequently that I can't keep up.

Space

So how do you get these backgrounds, other than buying them from someone else? Where did they first come from?

I prefer the symmetry of the Don't Starve Titlecard

THIS

There are rumors about one SECRET background. It's too majestic too describe it with words, but - just to give you an idea - it features GabeN, whipped cream and - most prominently - banana hammock.

Sanctum 2's The Wilderness is amazing, but too pricey for me at the moment.

I'm using Tower at the moment, I really it too though. :)

edit: Wilderness is now affordable, last time I checked the lowest was sitting at around $20. xP

I like the FTL ones. Trine 2 ones are cool, too. The Borderlands and Strike Suit Infinity ones are a real let down though, they look like some intern just phoned them in.