I few people I've shown this tip to recently have been surprised - so I thought I'd share it.
If you are developing any Dynamics CRM Solution, you are always going to want to test out security and role based access. The simplest way of doing this is to log on as multiple users, each with a different role, to see the effect of your security configuration changes. This can easily be achieved by using the 'Extended Context Menu' option 'Run as different user'
1) Hold down the Shift Key whilst 'Right Clicking' on Internet Explorer
2) You will see the 'Extended Context Menu':
3) Use the 'Run as different user' option to start a new Internet Explorer session as a different CRM User.
Simple but effective!