On Arqade, there's a button allowing to log in with Steam account. This button is missing from other sites, so users need either to type Steam OpenID address manually or to add another login option. Both options are not really convenient for users coming from Arqade to other SE network sites.
Also, Steam is used very often by game developers, so it would be very useful to have the Steam login button on Gamedev and Stack Overflow.
So, SE team, could you add a button to login with Steam on all sites, at least under "more login options"?