1. Phone:
Hold O: Insert a plus sign (+) when typing a phone number
Alt+X: *** an extension to a phone number
Alt+letter key: type a letter in a phone number field
Space+Enter: View the last phone number you called; Send:dial the number
Hold Send: view your contact list on the phone screen

2. Messages:
Within a Message
Press R: reply to a message
Press L: reply to all
Press F: forward a message
In a message, highlight the contact. Press Q: view e-mail address of a contact/view display name again (toggles)

3. In a Message List:
Press Enter: open a highlighted message
Press C: compose a message from a message list
Press Alt key and U: mark a message as opened or unopened
Press Alt key and I: view received messages
Press Alt key and O: view sent messages
Press Alt key and V: view voice-mail messages
Press Alt key and S: view SMS text messages
Press Alt key and P: view call logs
Press Escape key: view all your messages again

4. Moving Around a Message List:
Press the Space key: move down a screen
Press the Shift key and the Space key: move up a screen
Press T: move to the top of a message list
Press B:move to the bottom of a message list
Press N:move to the next date
Press P: move to the previous date
Press U: move to the next unopened item
Press J: move to the next related message
Press K: move to the previous related message

5. Typing:
Press Space key twice: insert a period (next letter is capitalized)
Hold letter key: Capitalize a letter (holding capitalizes)
Hold Alt key and Character key: type an alternate character on a key
Hold letter key and roll trackball: type an accented or special character
Press a number key (no alt): type a number in a number field
Hold Alt and press number key: type a number in a password field
Press Alt and Left Shift key: turn on NUM Lock
Press Shift key: turn off NUM or CAP lock
Press Alt key and Right Shift key: turn on CAP lock
Press Space key: insert an @ or a . when in an e-mail address field
Press Symbol key: type a symbol
Press Shift and roll Trackball: Highlight a line of text
Press Escape key: cancel a text selection
Press Shift key and the Delete key: cut highlighted text when typing
Press Alt key and click Trackball: copy highlighted text when typing
Press Shift key and click Trackball: paste highlighted text when typing

6. Wi-Fi:
Press Menu key, click Set-up Wi-Fi: scan for available Wi-Fi networks
Press Menu key, click Manage Connections, then Wi-Fi box: turn on Wi-Fi
Press Menu key, click Manage Connections, then Wi-Fi box: turn off Wi-Fi

7. Search:
Type contact name or initials with spaces: search for a contact in Address Book
Press S: search for text in a message
Press F: search for text in an attachment or web page
Press F (in text view or text and slide view): search for text in a presentation attachment

8. Attachments:
Press F: search for text in an attachment
Press G: move to the last cursor position after closing and reopening an attachment

9. Spreadsheets:
Press G: move to a specific cell
Press Space key: view the content of a cell
Press V, Highlight a worksheet, Press Enter key: switch worksheets
Press H: view hidden columns or rows
Press H: hide the columns or rows again

10. Presentations:
Press M: switch presentation views
Press N: move to the next slide
Press P: move to the previous slide
Press G (in text view or text and slide view): move to last cursor position after closing and reopening a presentation attachment

11. Browser
In Go To dialog box, press Space key: insert a period (.)
In Go To dialog box, press Shift key and the Space key: insert a slash mark (/)
Press O (in browser): open the browser options
Press Escape key: stop loading page
Press D: hide the browser
Hold Escape: close the browser

12. On a Web Page
Press G: go to a specific web page
Press H: return to the home page
Press K: open the bookmark list
Press A: add a bookmark
Press I: view a list of web pages you've recently visited
Press R: save a web page to a message list
Highlight link and press L: view the address for a link
Press P: view the address for a web page
Press S: save a web page to a message list
Press Enter: follow a highlighted link
Press U: hide the banner
Press U: view the banner again
Press X: view a thumbnail version of a web page (press any key to return to normal view)

13. Navigating within a Web Page:
Press Space: move down a screen
Press Shift and Space: move up a screen
Press T: move to the top of a web page
Press B: move to the bottom of a web page

14. Camera:
Press Right Convenience key (default):
Roll Trackball Up/Down, press Volume Key Up/Down: Zoom In and Out
Press Space: change flash mode for a picture
Press Symbol: change the size of the viewfinder

15. Media Player:
Press Mute: pause a video or song
Press Mute: resume playing paused video or song
Press N: play the next song in a category
Press P: play the previous song in a category
Press B: rotate a picture
Press I: zoom in on a picture
Press O: zoom out on a picture
Press W: return to the original picture size

16. Blackberry Maps:
Press I: zoom in on a map
Press O: zoom out on a map
Press U: view status information at the top of a map
Press U again: hide status information at the bottom of a map
Press Space: view tracking information at the bottom of a map
Press Space again: hide tracking information at the bottom of a map
Press N: move in the next direction on a route
Press P: move to the previous direction on a route

17. Calendar:
Press C: schedule an appointment
Press A: change to Agenda view
Press D: change to Day view
Press W: change to Week view
Press M: change to Month view
Press Space: move to the next day, week, month
Press Shift key and Space key: move to the current date
Press T: move to a specific date

and i'm spent...so there you have it...almost every possible shortcut for your 8320...hope this helps
Press G:

Hard reset

ALT + Right Shift + Del

Key shortcuts:

A or C = phonebook
S = search
F = phone profiles
W or B = browser
H = help
K = locks the keys
L = calendar
V = messages
M = messages folder
R = alarm
T = tasks
U = calculator
I = applications
O = options
P = phone

Some new additions thanks to the contributions in this thread:

T - Top of page (in browser)
B - Bottom of page (in browser)
Space - Page down (in browser)
ALT + Right Shift + Del = hard reset
D - Memo pad
U - Switch between hide/unhide in title bar (in browser)
ALT + NMLL = numbers instead of bars for signal strength