jprusik
What it does:
Pulls a list of games for you and each of your (publically viewable) friends on Steam and returns the Steam games you have in common that have multiplayer features. From this list, you can see what your friends' favorite multiplayer games are, if they're logged in, and even send them an IM through the Steam client (must be installed).
Example:
http://www.mysteamgauge.com/friends?username=monkeyagent
Issues:
-The app sometimes gives up mid-process. I think there's some rate-limiting mucking things up on Steam's end. I'm still working on it, but it doesn't happen too often, so try again if you get an error page and you're sure your username is correct.
-It takes a while to load. If you have more than 30 or so Steam friends, it may take several minutes.
You might try it on your smartphone if you can - I still need to work on the mobile layout, but it shouldn't look terrible.
I've actually collected a few other data points for each game as well, but I haven't figured out the best way to visualize / categorize them yet.
(You'll notice "ClassyNemesis" is my profile name, but my account profile still links to http://steamcommunity.com/id/monkeyagent )
Another interesting fringe case: Half-Life 2: Lost Coast is now only available via a $40 bundle, and is listed under that cost, but is actually just a pack-in bonus to the various Half-Life 2 bundles. How do I represent that? I originally had the $40 listing but updated it to "-" to reflect that the pricing isn't available.
Here's the summary I posted over on the Steam forums:
What it is:
Steam Gauge will let you get a summary of all the games/apps/etc listed for your Steam account via the Steam Web API. It returns information about those games including hard drive space requirements and cost (base store value, not what you actually paid).
Features:
-The list that is constructed allows you to individually select/de-select apps.
-There is a graphical representation of collection percentage selected vs total.
-There are pre-built options to select only a given app type (game, app, movie, etc).
-The app table allows you to sort the list by title, id number, hard drive space, type, and cost (just click the headers).
-If you don't have a vanity username set up, you can use your steamID64 number instead.
-If game information is missing from the database, it automatically adds that id to the list of apps to update in the next database refresh (simply using Steam Gauge helps make it better).
-Finally, you can export the results of Steam Gauge to a csv file, so you can manipulate the data however you wish.
Requirements:
-For now, your profile needs to be public.
-Javascript must be enabled on the browser.
-If you use a relatively modern browser, the whole experience is going to look/work better.
Limitations:
-The hard drive values are based primarily on the published requirements (where available) and is otherwise based on manual data checks of game install size.
-The database still isn't complete, especially for new games, and weird exceptions. It should still be helpful for general estimates, but the precision is limited to the data available.
-The mobile layout still needs a little work but should function properly.
-The "Value" column represents the base cost of the game, not what an account owner paid.
Future plans:
-Add more game information including genres, controller support and multi-player capabilities
-Add submission flag for games with missing/incorrect data to help crowdsource what I can't scrape