Carry around a thin stack of cards for a week use one everyday to jot down notes, make small collages, do quick sketches, or just for ideas you may have. At the end of the week you can sort the cards into themes, create a to do list, bind them together or file them away.
Why not try this for a month instead and see what happens. At the end of the month you will have a whole stack of cards with ides, mini pieces of art, or even projects you can start.
Note cards are also great for creating a travel kit, instead of bring a big book along all you will need is a pack of cards. You could work on a new card everyday and come home with a trip full of memories.
Using the cards might be a nice break from keeping a traditional journal, what other non traditional journal ideas can you share with us?