If you use a PowerPC processor you may want to try TenFourFox.
OS X Leopard (10.5), or greater: 32-bit and 64-bit Intel
If you use an Intel processor you can use Opera: Intel-based Mac: Opera (thanks to Cybermatatu for this one!) with older Flash 10.3 (beware, Flash 10.3 is an archived version and is no longer supported nor updated with security fixes by Adobe). PowerPC-based Mac: TenFourFox and no Flash.