Dropbox
CBS Sports for Fantasy Football
Pandora
Zombie Photo

Outdoor navigator
brightest flashlight
out of milk

nothing fancy, just what I need

RadarScope.
Waze
Rad Stat (HVAC control)
Go Payment

Making a phone call? Does that app still apply?

History Here: Historical buildings, points of interest, etc. Great while traveling.

Diners , Drive Ins and Dives: Another great app while traveling to find those greasy spoons from the TV show.

That reminds me, I use the hell out of Urban Spoon when traveling.

Top 5? LOL. You're a funny guy.

I installed the following on a new phone recently:

2X Client (RDP)/AndFTP (FTP/SCP)/ConnectBot (telnet/SSH)
Google TV, Tivo & XBMC remotes
Fing/Network Info II/Wifi Manager
Aldiko (books/reader)
Netflix, My Netflix Q
ConvertPad, Real Calculator, Perfect World Time & Stopwatch/timer
Google Authenticator, PasswordSafe
Google Drive/Play Music/Voice/Mail
SoundHound, IMDB
MessagEase (tap'n'swipe 60 WPM replacement keyboard) and word prediction dictionary.
AutoBoy BlackBox (for track days)
Bar Code scanner, various inventory programs
Phonealyser (graphs call usage etc.)
Flashlight

That's pretty much bare minimum - I'd miss any of those if they weren't there. I probably spend the most time running Solitaire out of any of those. :)

There's a whole bunch of apps I installed in the past, most, though cool, are not in the same "needs to be there" category

gas buddy
pandora
flashlight
cozi
craigslist

oh yeah and nascar app

Map My Walk/Run/Ride - a GPS 'follower' that tells you how far you have run/walked/ridden your bike. Great for planning (shows things like elevation) keeps track of all your activities, calories burned...

Dropbox
Yelp
Maps
Evernote
Quickoffice
Facebook
LinkedIn
Pandora
Vendormate