I'm using foobar2000 as a medialibrary handler, often converting audio for different portable devices and miss these fields. Hard drives now are cheap, so I have a "cache" folder where I store already encoded files and subfolders "aacs" "mp3s" and "oggs", which I select manualy before encoding. This is not some big problem, but I think existence of some kind %convert target format% field would be handy. %convert preset name% could be helpful for these people, who has different devices with same format but different supported features or quality requirement or someone, who likes to find compromises like "store all discography of selected performers in best possible quality".
So, my suggestion is to implement 2 convert time only fields, so
%convert format%/%convert preset name%/[%album artist%/][[%date% - ]%album%/][$num(%track%,2) - ]%title%
should resolve to something like
Ogg Vorbis/Ogg Vorbis, 192 kbps, q6.0/Moby/1992 - Moby/01 - Drop A Beat