Comment by wlkr

I think the biggest innovation of this kind that I've seen in use (anecdata, of course) is the number of commuter bikes fitted with belt drivetrains (Gates Carbon Drive) paired with internally geared hubs. The reduction in maintenance effort is purported to be significant and it's not only limited to high-end bikes (plus it can be retrofitted although non-trivially for the majority of frames). When the cog wear becomes too bad on my single-speed I'll look into fitting a belt drive, if possible.