Louisa Pearson: "These apps are starting to sound like having me with you at all times" YOU'RE walking, you're shopping, you're doing one of 100 activities when it hits you. You're thirsty. Do you buy a bottle of water or do you check your Tapwater.org app and find the nearest location that'll let you fill a receptacle for free? For the second option to work, you need two things - an empty bottle and a smartphone or other app-hosting gadget. Assuming you have these, technology just helped you on your quest for greener living. I still don't have a smartphone, thanks to my aversion to signing up to a monthly contract, but I recently invested in an iPod Touch. If you're as antisocial as me, this is the perfect solution - it takes photos, videos and lets you access the internet and e-mail while never having to answer a call from someone who wants to help you claim insurance for an accident you were never in. It's fantastic, unless you're nowhere near a wifi hotspot, at which point you start cursing yourself for being such a tightwad. Regardless, this voyage into the modern age has introduced me to the world of green apps, and what a veritable grotto of ethical delights it is. If you're out shopping, the app you want is from the Ethical Company Organisation, whose mobile version of its Good Shopping Guide lets you compare the environmental credentials of different brands. How did you get to the shops? Perhaps using the WalkIt.com app, which helps you plan urban walks and gives details of journey time and C02 saved as compared to other transport. The National Cycle Network also comes in app form, via www.sustrans.org.uk (this site will direct you to either the iTunes store or Android market - all apps mentioned here are available from one or other of these sources, and most are also available in website form for those in app denial). If you simply must drive, the greenMeter app will help rate how green your technique is - pop it in your iPhone car mount and note that it will not look favourably on rapid acceleration or sudden braking. These apps are starting to sound like having me with you at all times, pointing out what you're doing wrong - I wonder if I could find a developer to help me work that concept up? Meter Readings is a nice, straightforward app where you enter readings for gas and electricity and it works out your usage, costs and savings. Moving in to the kitchen, LoveFoodHateWaste.com features recipes and tips to help us remedy the wayward situation whereby Scots throw out 566,000 tonnes of food and drink each year. I was particularly intrigued by the "Free-lunching" feature on the website, which I thought might encourage reckless bin-raking, but instead it offeres suggestions for making soups and salads from the leftover bits and pieces in your fridge. Being green isn't all about carrying a wearisome burden on your back; it's about enjoying nature too. That's not to say your trips into the great outdoors can't be educational as well as fun, and the Collins British Wildlife Photoguide app is the equivalent of taking a subdued David Bellamy on a walk, identifying 1,500 different species of flora and fauna. My final recommendation is a form of body armour for greens. Originating from.skepticalscience.com, it gives you an answer for every argument posed by disagreeable climate-change sceptics. "It's not us, it's the sun," says some bore. A quick glance at the app and you can rebuff them with, "I think you'll find that the sun's output has barely changed since 1970 and is irrelevant to global warming, my good man." Happy apping.