Saving jam, honey and pickle jars with screw top lids is my latest idea. Actually I got it from my DS.
They are ideal for keeping leftover bits and storage of small amounts of things (nuts, dried herbs, etc)
The advantage over tupperware is that when you store leftovers in them in the fridge (a) they take up less space because they are upright, rather than flat (b) you can see what is in them immediately (c) when you put them in the dishwasher, they dry completely using their own heat, unlike plastic, which always needs an extra wipe with the teatowel because it cools off so quickly and the last drops don't evaporate.
I know the re-using of screw top jars is as old as the hills, but I wish I'd started doing it before I went to any tupperware parties back in the 70s and 80s.