1. iPhoney

iPhoney

2. W3C mobileOK Checker

W3C mobileOK Checker

3. iPad Peek

iPad Peek

4. Modify Headers Add-on for Firefox

Modify Headers Add-on for Firefox

5. Adobe Device Central CS5

Adobe Device Central CS5

via: http://sixrevisions.com/tools/10-excellent-tools-for-testing-your-site-on-mobile-devices/