Some of the cool vim tricks and tips

I use vim everyday. So much that even to write notes I use vim!
Here are some of the awesome tricks I have come across:

1.  Suppose you have opened a file for which you don't have permission. While saving it will say "E212: Can't open file for writing". Now instead of saving this temporarily in another file and then saving in this file, you can do this:

:w !sudo tee %

2.  You can edit binary files like in hexedit 

:%!xxd

3. Easy diff between two files. Say there are two files 'a' and 'b'. To find the diff of 'a' with respect to 'b'

:vert diffs b

4. See command history

q:

5. Execute command while still in vim.

:! <command>

Here I am compiling and running cpp file without closing it.

6. Autocomplete whatever you are typing in insert mode based on the words you have typed before:

Ctrl+n

7. Directory Listing without NERDTree

:vsp %:h

8. Indenting code

=<next position>

For example, 
To indent the current line, press ==
To indent the code till next closing flower brace, press =}

Here is an example of indenting the entire code block. Place the cursor on { and then press =%

Before

Indented

9. Make searching as you type instead of after completing typing the entire thing

:set incsearch

10. Download and open source code for a given url

vim http://google.com

I usually use this to quickly view responses of my web pages.

vim http://localhost/path

I will add more in the future.

Sources:
http://vim.wikia.com/wiki/Best_Vim_Tips
What are the dark corners of Vim your mom never told you about?