For the last two weeks I've been playing around with an app on my Ifern (theres an android one too) called myfitnesspal and have found it pretty useful/easy to use.
I guess its fairly standard fare in that you enter what you eat every day, and how much exercise etc.. and it tracks calories consumed/burnt. Its probably also wrong to a certain degree, but its been a really useful exercise in totting up what I eat over the week(s)... That friday night curry and 3 pints tots up more in one sitting than many days in total..
Anyway, I thought I'd mention it as its pretty easy to use (much less faff than other ones I've tried) and quite informative (well for me anyway). I'm clearly not the only one who likes it as it gets a 4.5 stars as an app - which is pretty rare...
(oh its free too..)