Yasis provides yet another scalable icon set.
Release 0.4.2 includes 24x24 filesystems and mimtypes to make it look better when you open/save a file or use Nautilus' list view mode.
Yasis is the current default icon set for Dropline GNOME, it's still under mid-active (if that exists) development, but there hasn't been a release in a while.
To install the iconset drag the .tar.bz2 file and drop
it in the theme preferences dialog.
Unpack the iconset to ~/.icons or /usr/share/icons like this:
# tar -xvjpf yasis-.tar.bz2 -C ~/.icons