Iv come across some great apps in the last few days, and i thought id share my thoughts on them. There has been forums on this in the past but they are a bit outdated. Prices in USD.
Shazam (free) - Hold ur iphone up to the radio or other music source, and this app will tell you what song is playing! Samples the audio for about 10 seconds, then shows artist, title, album. Links the song on youTube. Works amazingly well, i tried with a buch of obscure songs and it found them all. Requires internet.
AroundMe (free) - Shows bars, petrol stations, movie theatres etc near your location. It can show them on a map. Works suprisingly well, comprehensive database for NZ locations. I tried it out in my area, and it found all the places i could think of + more. Impressive.
Guitar Toolkit ($13.99) - Full tuner, fretboard, comprehensive chords database and interactive metronome. Lovely interface. Tuner works very well, better than my chromatic tuner.
Graphing Calculator ($1.29) - Scientific calculator with full set of functions. Can graph equasions ( y(x)).
Units (free) - Can convert between units. Includes imperial and metric. Covers distance, flows, temperatures, weights, energy plus many more.
Google calendar/contacts Sync (not an app) - This has been really handy for me, syncs ur google calendar with ur phone calendar. Also gave me a way to consilidate all of my contacts into one medium free database.
I would love to hear everyone elses favourite apps. Personally im not interested in games (would rather play on the PC), but feel free to post any that interest you. Most of these apps are things i would not think to search for, but im very glad i stumbled across them. Im sure theres many more that would be usefull to.