iBird Explorer Canada
99¢ (limited time), by Mitch Waite Group
You don't have to be a serious birdwatcher to enjoy iBird. Actually, it's probably better if you're not already a bird nerd, because then you won't be mad about the app rendering the hobbyist's hours of study and fieldwork obsolete. When you see a bird, use the app to identify it by colour, shape, location, etc. and confirm by listening to audio of its call. Usually $10, as of this writing iBird is on sale, so there's an incentive for early birds. Word.
Star Walk — 5 Stars
$2.99, from Vito Technology Inc.
This app shows why mobile devices are a whole new communications medium, rather than just a small version of the internet. Fire up Star Walk, point it at the starry sky, and get an info overlay that tells you what planets and constellations you're seeing. Pinch-zoom with your fingers for more deets. Or search for a celestial body---try ISS, the international space station---and the app will point an arrow to let you know where it is right now. Turns camping into a chance to watch god's TV.
$1.99, by John Sherry
A knot is a form of ancient technology that's still useful today. Especially if today you're stranded on the banks of a remote river, all your gear and food swept away by the current, with only a fishing hook and a ball of twine to provide food and shelter until the search party finds you. (Note: If that's your expected usage scenario, study with Pro-Knot before you go, working through the 70 knots using the illustrated step-by-step instructions until you've earned your Knotty Camper merit badge.)
$9.99, from Groundspeak Inc.
A ridiculously easy way to join the global orienteering-for-pirates phenomenon, Geocaching turns any walk in the woods into an adventure. Do a search, and the app will list the 20 nearest geochaches (small-scale treasures and puzzles which other geocachers have hidden); choose one, and follow the compass and distance meter to the target. Click in the app if you need a hint, then log your discovery and set off on the next hunt.
99¢ (limited time), by GOAPPS
The iTunes Store has dozens of anti-mosquito apps, all working off the idea that an iPhone can make a high-pitched noise to repel bugs without bugging you. The theory is solid, at least to a person with no background in audiology, insects or insect audiology. I am such a person, and I'm only a bit ashamed my dread of mosquitoes makes me unable to do any field-testing. Slap appealed because of its five-star rating; "introductory" sale pricing that has lasted since last summer; and claims to be the only app in the category that works while the phone's asleep. I bought it hoping to never get a chance to use it, but I'd love to hear how it goes for you. Scratch me a line at email@example.com or on Twitter at @kyles.