Codeigniter seems to break $_POST of '£' character (Pound)
This appears to only affect users using the latest version of MAMP and when using PHP 5.3.5. The current workaround is to go to the MAMP control panel and use the earlier version of PHP 5.2.17
For more details see: https://bitbucket.org/ellislab/codeigniter-reactor/issue/214/problem-when-inserting-special-characters