If you really want to, you can now delete games from you Steam account.
Some people have more games on Steam than they'll ever have time to play. Some of these are just terrible friend joke gifts, bundle extras they couldn't get rid of, or maybe games they bought but no longer wish to own.
Steam now appears to have added an option for removing any abomination you do not wish to have associated with your Steam account. Remember, doing this does not get you a refund, it just removes it from your library.
The user also notes that games that were part of bundles can't be removed individually, and the whole bundle has to go. This is true for both Steam bundles, and ones that all shared the same key - such as the ones offered by some bundle sites. Don't fret though, the page will show you everything getting removed when you request a game to be removed.