For me, lemon squash to encourage myself to drink between 2 and 3 litres a day - it works. The other product is Highlights Hot Chocolate, it feels like a bit of a treat in the evenings and it's filling because it is hot. I am not delighted that with both of those products I am consuming a lot of chemicals and artificial sweeteners, but I can't see a cheap and quick alternative.
I also try to have sugarfree chewing gum handy and Oraldine, as my breath is always beyond minging when I diet, which is one of the things that often makes me quit.
I'd love to hear what are your absolutely must have products that help you stick with your diet.