New suggestion, where we do item giveaways.

Gameminer has this currently. There may be some other sites as well, I am not sure.

No happening here, because it would be impossible to manage. Would get people claiming to have given X item for contribution, and without any way to prove otherwise.

I only know about Gameminer.

Ew :)
(For reason Delta noted.)

that's probably a really bad idea, since most people will sell the item on the market...

main principle of SteamGifts is that you must activate won games on your account - thus you cannot use the site for personal monetary gain (you can use it to get more games on your account, but you cannot use it to earn money). Items can be used, also there is no system for permamently attaching them to your account, not to mention people having private inventories and steam API not returning inventory on syncing with SG like it does with games - thus item GAs could not be monitored whether winner is using item for temselves or selling it for profit. Thus people would start using SG to earn wallet money - it would also bring even more bots, because items are easier to turn into money that for example game keys you cannot be sure if were used or not.
Plus add what Delta said to what I'm saying - if CV value of such GAs would be anything but 0, people could easilly cheat their way to earn CV - you make fake GAs with knifes worth hundreds of $ - your fake alt accounts win them - no way to tell that there is reallly a CV fraud. With games it is easy - you check game activastion.

Along with all the reasons everyone else noted, item prices fluctuate a lot. It would be hard on the server to have to update prices every minute.

Another thing I just thought of ane mention in reply comment to Toast above - now on SG single item as it must be activated can earn CV only once. If you purchase 10$ worth game on Steam it will generate only 10$ CV across the entire website.as items cannot be redeemed and perma-attached to an account. Plus like I mentioned we cannot monitor if the item is in person's inventory. So - when in games if you purchase 10$ game you can earn only 10$ CV, with items you can trade it back and forward with your group of friends in private or group GAs - if you buty 10$ worth item on the market instead like games it earning you 10$ CV it can earn you unlimited amount of CV.

i think it's a good idea, but as said before, how will you know the end?
only if you put into a seperate system and not the same cv. but i think there will be less people who wants to give.
cause you have the game, what you going to do with another one? but items? hell, sell. or dump on a bot in steam