JennieG, I've tried Vegemite and cheese sangers but not with lettuce. I would probably like it.

Since we are pivoting into a slightly different topic, I have to also mention my other favourite sanger is nasturtium leaves with just butter or margarine, or sometimes with cream cheese as well, on white bread (which I don't usually eat, or a wholegrain bread with a less over-the-top flavour). I can credit my Mum with that one too. Our back yard is overflowing with nasturtiums. I'm going to get out there and pick some lovely, tender young leaves. Mmmm!! Yum!!

Nasturtium leaves with PB would probably not work, but then again...maybe I should try it, given that other people are suggesting mayo or mustard with PB.