Some essential apps, imho:
-Titanium Backup: Backup ALL apps, Market links, remove bloatware, etc.
-EasyTether: Tether to Windows, Mac OS X, Ubuntu, PS3, Wii, 360 - no tether fees!
-Google Voice: Great visual voice. Voice mail transcripts are great!
-Swype: Use swiping gestures to slam out mega quick texts (touch screens only) Absolutely essential, imho
-Netflix (no brainer)
-Flash (no brainer)
-Barcode Scanner: Use at least four times a week at Target
-Handcent: best SMS
-Gmail
-RealCalc: Nice little scientific calc
-Vignette: Hands down best camera on Android market......imho
-ES File Explorer: Very useful, simplistic, treed file exploration
-AlarmDroid: It's my daily alarm clock
-Craigslist Notification: How I beat AznKhmerBoi to all the CL deals in our area
-Dolphin Browser HD: the most popular browser on Android - though I'm a tad partial to Opera's new update
-Dropbox: (no brainer)
-imo IM client: how I talk to Hobie, sevin, and mjmjr on the go
-MyCast Weather: The paid version has superb doppler!
-Paypal: essential for racketboy wallet drain on the go
-Out of Milk: My primary shopping list - Supports voice!
-Mint: Great mobile banking management
I would consider these all essential, noise, and use the majority of them daily.

