A friend of mine pointed me to the release of the Source Code Pro font from Adobe, which can be found on github.

I told urxvt to use the font using the escape sequence

printf '\33]50;%s\007' "xft:Source Code Pro"    

which looks like this:

Source Code Pro in a terminal

(this required a new urxvt instance to be started, because urxvtd seems not to pickup font additions during run)

As the resolution on the MacBook Air is "only" 1440x900, I am normally using the fixed font to have a lot of space for the text. This is how it looks like:

Source Code Pro in a terminal

Putting both terminals side by side, I am loosing 12 rows from the size different.

As the Source Code Pro font is not designed for this small size I happily continue to use fixed for now.

Besides being to large for my use case, Source Code Pro could become a quite interesting font for coders.

If you are interested in more usable fonts for terminals, have a look at the Xorg terminal emulator font list.