General tips

Disposable email

If you are signing up for a lot of accounts you can use a disposable email. You just enter the email account you want for that second, and then you can view it. But remember, so can everyone else.
https://www.mailinator.com

Base64 encode/decode

import base64

encoded = base64.b64encode("String to encode")
print encoded

decoded = base64.b64decode("aGVqc2Fu")
print decoded

Quick Base64 Decoder

echo aGVsbG8gd2hpdGUgaGF0Cg== | base64 -d

Metasploit Slow Search Fix

db_rebuild_cache

Default passwords

http://www.defaultpassword.com/

Getting GUI on machine that does not have RDP or VNC

You can forward X over SSH.
http://www.vanemery.com/Linux/XoverSSH/X-over-SSH2.html

Metasploit shell upgrade

In metasploit framework, if we have a shell ( you should try this also, when you are trying to interact with a shell and it dies (happened in a VM), we can upgrade it to meterpreter by using sessions -u

sessions -h
Usage: sessions [options]

Active session manipulation and interaction.

OPTIONS:

-u <opt>  Upgrade a shell to a meterpreter session on many platforms