How do you manage your game keys?

I have keys for games all over the place, I had a collection of them until my hard drive crashed a while back, now I have no idea what keys have been used and what haven't, if I try and activate them on steam and they are in fact unused will they activate if I already own the game, or will an error pop up?

Get 4-5 and do a Key Drop.

I don't have that many keys... I was going to say, then I decided to look in my accounts.
I have 78 unused keys(steam and desura). And I don't keep track of them in any organized way, just memory.

I have no idea TBH. I may just one day post all the keys I have, both used and unused and allow a battle royale for everyone to attempt. :/

I am sitting on 0 keys right now. I only buy bundles that have mostly good games (in my opinion).

Just a text document on my desktop.
i have multiple keys for the same games, so my format is like this:

[Name of game]:

[key]
[key]
[key]

[Name of game]:

[key]

[Name of game]:

[key]
[key]
[key]
[key]

Text document, automatically backed up to Dropbox.

.txt on skydrive, and my usb drive when I wanna hook a friend up with a game.

I redeem everything I can, the rest I list in .txt until I have given them away, then I delete them. I don't see how it could be any more complicated than that.

I usually have a running email to myself, so I can redeem them from anywhere. Although, I haven't had any extra keys in a while, so I haven't needed to. But when I randomly looked in my email recently, I found an old email with three keys and I really don't know if they were ever used.

simple. i create a list on my computer.

In the same spreadsheet where I keep a list of the games I own too.

Google docs excel sheet

Just a wordpad document. Game Name: XXXXX-XXXXX-XXXXX then (used/not used) in brackets. lmao

I keep them all on Evernote. That way it's accessible from any computer.
If it's a steam game I use the format of:
Game
Code

If not, it's:
Game (Platform)
Code

Then at the bottom, after a line is the used keys pile. After I use a key I move it down into that pile then write how it was used (for example: "gifted to Sinovera"). That way if I'm going through old bundles and I can't remember if I've used a key or not I can refer to that list and see that it has/hasn't been used.

*.xlsx file with a lot of information about games and keys :)

very similar to yours, as a Google spreadsheet, but I also have a link directly to the bundle key redeem page and each bundle is a row with all games in the bundle listed. separate bundle sites on separate sheets.

Desktop full of .txt for each occasion of obtaining keys.

i usually use 'em but if I get a key of something I already have/don't care for I just plop it in a sticky notes margin and give it to a friend or whatever later

for those game/betas access that i haven't activate yet i gather it and make a note on my email, that or simply the email that contain it. much easier to access from everywhere including from my cell.

Right now I got all my keys in a Notepad++ file, secured with a difficult password which also is encrypted. Just to be secure, right?

i just dont redeem on humble bundle so i know that they are unused

A Google Spreadsheet with them broken into price tiers: $0-19, $20-$39, $40+, and then ones that I haven't decided on keeping or giving or am holding for a specific reason. I use the ones from the price tiers as prizes and such when my friends and I play.