App-licable.

A friend just got an iPhone, and I offered to recommend some aps to him. These are my go-to apps. I do experiment now and again, but these are what I come back to:

App Name	App Type	App SubType	Comments
iExpenseIt	Finance	Expense tracker	I use this for tracking the money I spend on shirts and cocktails and stuff (where I need to know it balances out). Also useful when you think "It's the end of the week. Where's all my money?"
Worms	Game	Action	Just like the Game Boy, DS, or whatever version with all weapons and levels.
Space Deadbeef	Game	Arcade-Style Shooter	Side-scrolling shooter. Fun times.
Spore	Game	RPG	A mini-version of the real thing.
Flight Control	Game	Skill-based	A very popular Air Traffic Control game. Far more fun than it sounds.
Dactyl	Game	Skill-based	Very quick I-need-to-kill-5-minutes game. Defuse the bombs in time!
TapDefense	Game	Tower Defence	A good (free) beginner Tower Defence game, just enough to get you hooked.
FieldRunners	Game	Tower Defence	The next step, with place-anywhere towers and path-building.
GeoDefense	Game	Tower Defence	The big daddy. Tower Defence with Geometry-Wars-style effects and a crazy difficulty level
Star Defense	Game	Tower Defence	Tower Defence in 3d on a globe. A good game for when you're sick of Geodefence kicking your ass.
KarmaStar	Game	Turn-based Strategy	Cute, quirky stat-based Strategy game involving dice-rolls & attacks.
I Can Haz Cheezburger	Humour	Picture Feed	For all your daily LOLs.
Urbanspoon	Lifestyle	Restaurant Finder	Great for picking where to eat. You can also use the randomise feature to come up with something out of nowhere.
Stanza	Reader	Book Ereader	Reads PDF e-books (for free). Also can have new (pirated) ebooks uploaded from a desktop app.
iVerse	Reader	Comic eReader	Actually a series of apps, each one representing an issue of a comic. Some free, some not.
Ebay	WebApp	eBay	Just what it says on the tin.
Facebook	WebApp	Facebook	Just what it says on the tin.
Twitteriffic	WebApp	Twitter	My go-to Twitter app, until the 3.0 Software update made it go screwy on the iPod touch. Easy to use, plus easy re-tweeting and marking for later.
Twitterfon	WebApp	Twitter	Twitter app, part two. Visually similar to Twitteriffic, but actually works on the touch. Also has auto-twitpic, auto-friend-name-add, and other nifty features.
TweetDeck	WebApp	Twitter	Organises tweets into columns. Some like it, but it's not my favourite.