PE – cusco is in a valley, get a window seat when flying In or out and have your camera handy
SLR – If your main camera is an SLR, consider not bringing it. There are places in the world where it's value will exceed the annual income of the locals. If you do bring it, aim for a lens that covers most needs without having to change. Canon has an 18-200 that works well for most situations. Also consider bringing a small point and shoot for the situations it's not safe to make the slr visible.
NZ – pahia, the pippi patch hostel is pretty crappy. Only stay there if there's a group of you and you can fill a room. Otherwise there's a hostel across the street with free bikes and canoes. Can't remember the name but it was in the lonely planet.
iPhone – iPhone is a great travel device. If possible get one that's unlocked ( or get yours unlocked before you leave ). The maps feature alone could save your life, but be warned: without cell access the gps does not work. It needs to talk to the towers to figure out which gps satelites to look for.
USA – iPhone, if your trip is short, consider adding the international data package to your AT&T phone plan. It's $25 a month for 20 megabytes which is enough to chekc your mail on occasion (make sure it's not set to auto check mail!) and to load up the local map in a pinch.
iPhone – when wifi is available, cache the maps to the street level for wherever you are. Free Maps Often suck, and the google ones don't.
PE – maccu picchu, if you're physically fit, you're going to want to go to wannu pichu, the mountain overlooking maccu picchu. They limit the # of people that can go up there to 400 a day in 2 batches of 200. The first one is at 6am, and is the one you want to be in. 2 choices. Either walk up the inca trail to arrive there about 5:30 ( leave at 430 I'm told) or be in line for the bus at 4am. (buses start leaving at 530). We got to the bus line at 430 and just missed he cutoff by about 20 people. Once in with your wannu picchu stamp, run over (carefully, slippery when wet) to that gate and get your time slot for going up. The earlier the better as the sun makes things hot pretty quickly. You'll likely be done with all of machu picchu by lunch time, which is a good thing. Other things to check out: the inca bridge. About 30 min roundtrip depending on how many photos you take. The signin form is so they know if you made it back ok, they really do lose people, so be careful. The bridge itself is a holy shit kind of thing though, and you can bet that whoever thought to build it in the first place either had lots of minions he didn't care about, or was on a significant dosage of Incan acid. Mount machu picchu is also an option for the serious hikers. Likely best in the morning as the sun will be behind you when taking pictures, it seems to be about 3 hours for the capable climber. Also. Bug spray! Once you're sweaty from all the hiking around the bugs will find you so be prepared.
PE – stay in the barranco backpackers if you can. They'll set up a taxi from the airport for you $16 and chris who runs the place has lots of good info. It's a great first and last stop in Peru for backpackers, but does often get full on Saturday nights (at least in jan) so keep that in mind. Also, don't go to the beach at night, not safe.
PE – learn Spanish. I got a western europe phrasebook covering all the languages for the countries I'm going to visit. It was a great refresher for my ugly Spanish, but it gets me the respect for trying. I also save $ as many things are more expensive in English. A taxi ride in Lima has been 20 soles in English while 8 in Spanish. "cuanto por barranco central" works muh better than "how much to go to, uum, backpackers in barrrranco". Plus it's a conversation topic when in situations where they don't speak english. "que es" and then point. They will likely tell you, you'll learn something, and that akward silence is avoided.
PE- taxis. Don't take them unless they have their license plate number painted on the side of the taxi and a taxi sign on top. (or you arranged for it through a trusted means). It's not safe to take a gipsey cab, as there's a decent chance they'll take you to a very bad part of town and up the rate 10-20x what it started as or leave you in gang land.
PE – cusco, I don't remember exactly where, but walking distance from the main square was a market for locals. We walked through a covered market to get to this set of streets where hill folks were selling their warez on the street. Nobody spoke English, and I was the only white person in sight but it didn't feel unsafe (I wasn't alone!). And wow, the stuff for sale was amazing at astonishing prices. They likely charged us higher prices for being white with poor Spanish, but even double on 15 cents is only 30 cents if you get my drift. There were also massive bags of coca leaves for sale, which we found quite humorous.