pretty sure these are all free unless stated otherwise...
second the apple remote - this shit is the bomb, especially if you've got airtunes, but generally if you're cranking tunes and not in front of the computer
second XE for currency conversion, good widget also
second eBay
AirSharing is worth the money if you think you'll use it (use the iPod as a hard drive wirelessly, view office/pdf/rtf etc files)
*flicks through pages*
oh, fuck lightsaber. iwhip lite. this is no 'use twice and delete' app. this is THE pointless motion sensing novelty app...
as much as solitaire is gay, it works pretty good on the touch screen, i've got Sol Free
paper toss is an awesome free game... and flight control is a pretty cool game and apparently very addictive, i haven't played it much yet but grabbed it for a dollarish
lux touch for quick and dirty risk fun
second shazam - quite impressive really
flashlight is kinda useful, worth having on there, just cranks up a full brightness white screen
there's a couple of spirit level apps, i don't know how trustworthy they are but there's a stanley one that you can calibrate, i've got another called 'ihandy level' which i've not really tested out. stanley one looks better i think...
if you goto speedtest.net on the phone it sends you to the app store to get a free speed test app, not heaps useful if you're just on a touch i guess but good for the phone
there's one called pktCinema that has times for GU marion & arndale, kinda useful to have handy
NYTimes app is pretty good for a bit of news on the go...
i've not used it heaps so far but i grabbed one called 'urbanspoon' that seems to be a pretty good directory of eateries with ideas on price range and a few menus... i can see it getting used a bit
iiQuotaLite for anyone on adam or iinet (and some other isps i think ... good if you're not in internode) to check ur adsl usage
i grabbed an app simply called 'translator' also just incase
oh and got recommended 'the weather channel' as a replacement for the built in weather app, much more detail, i guess it's better, don't know how reliable the built in yahoo weather is? there's another simply one that is just called 'ausweather' that gives you a BOM feed, i'd use that if you don't want heaps of details. if you get the weather channel and can't find how to change from farenheit to celsius (i hope it's not just me), go to locations and scroll to the bottom...
i haven't yet unleashed the fury of peggle on iphone but i'll probably cough up at some point

... unless i jailbreak... dunno if i cbf... but there is turn by turn navigation software that's about $80 and a few other cool things that are serious $$ (like $30+)
maybe one day if i get bored but too busy to bother at the minute...