Common keyboard shortcuts for Cut, Copy and Paste

Generic/Apple
Cut: command-X
Copy: command-C
Paste: command-V

Windows/GNOME/KDE
Cut: control-X / shift-Delete
Copy: control-C / control-Insert
Paste: control-V / shift-Insert

BeOS
Cut: alt-X
Copy: alt-C
Paste: alt-V

Common User Access
Cut: shift+Delete
Copy: control+Insert
Paste: shift+Insert

Emacs
Cut: control-W (to mark) control-K (to end of line)
Copy: meta-W (to mark)
Paste: control-Y

vi
Cut: d (delete)
Copy: y (yank)
Paste: p (put)

X Window System
Cut:
Copy: click-and-drag to highlight
Paste: middle mouse button

How To Copy Images or Text From a PDF File

How to copy images from a PDF file isn't obvious from the menus and toolbar. The steps below will show you how it's done. The copied image can be pasted into another document or saved to your hard drive.

Difficulty: Easy

Time Required: N/A

Here's How:

1. Open a PDF file and go to the area you want to copy.
2. Zoom in on the area to be copied until it's the desired size. Images can only be copied at screen resolution (72-96 ppi).
3. In Acrobat Reader version 4: Click and hold down on the Text Select Tool button. A toolbar flyout will appear with three additional buttons. Choose the Graphic Select Tool from the flyout (third button).
4. In Acrobat Reader version 5: Click the Graphics Select Tool on the toolbar or use the keyboard shortcut G.
5. In the document area, drag a selection marquee around area you wish to copy.
6. Right click and choose copy, or go to Edit -> Copy, or press Ctrl-C on your keyboard. (Command-C on Macintosh)
7. The selected area is placed onto the clipboard as a bitmap.
8. Paste the image into another document, or paste it to an image editor and save it to your hard drive.

Tips:

1. To copy text from a PDF document, use the Text Select Tool and the text will remain editable.
2. If the text you wish to copy is in a column, choose the Column Select Tool. The column select tool maybe be in a submenu of the Text select tool.
3. You can also copy text with the Graphic Select Tool, however, it will be copied as a bitmap image and will not be editable as text.

Source: http://graphicssoft.about.com/cs/general/ht/copyfrompdf.htm