[TillE]

Just curious, which kinds of projects make attribution difficult? The worst I can come up with is that you'd have to include it in the small print at the bottom of an ad. Most other things (software, videos, websites) will have a more discreet place to shove all your credits.

In general, I think CC-BY is fantastic. CC-BY-SA is typically useless for anything except open source projects.

[JoeAltmaier]

Think playing cards with CC images, or business cards with CC logo. Small things with no room for the possibly-large attribution url.