I use it whenever my Internet is being wonky.

I only use it when I bring my PC to my parents home and I am too lazy to unplug the Ethernet cable from their PC and connect it to mine.

Then quit uploading a bunch of nude shots of yourself to Perez Hilton.

@jams: I...I thought my Internet could handle it...

If I don't have internet, I don't want to live!

I've tried, it's usually garbage though; can be quite frustrating for "steam-only" games. Though if I buy a game on a sale digitally from their store it doesn't have the same impact so I don't care as much if it doesn't work offline; but those few times I've bought a hard copy of a PC game that had DRM and it refuses to work I was aggravated. Still doesn't even hold a candle to this 24 hour bullshit, Steam might not work offline about half the time; XBone won't work 100% of the time after 24 hours with no internet; which isn't really that uncommon of an occurrence (let alone all the potential for the system going down).

I use it a ton. My roommate often wants access to some game or other that's on my account, so she'll log into it in offline mode. (Or vice versa; she'll be online doing something, so I'll just hop into offline mode.) As long as both of us don't wanna play multiplayer stuff at the same time, it works fine.

Bow down before my mighty internet connection, peasants!

Though Offline Mode has been helpful in a handful of situations.

I use it whenever my internet is down and I want to play a game on Steam. It's infrequent but it happens.

I had an internet outage for several hours on Monday but I did not play games on Steam. Instead I fired up the PS3 for the first time in a couple of weeks and played a bunch of games on that without issue. That's the advantage of a dedicated video game console, I guess.

I use it all the time to share my games with my wife so we don't need to both buy SP games.