Not to be done lightly, but if you need a break from spam attacks you can block visitors by country with this free blocking service for Apache Web Server. Simply select the countries you want to block and press the "Download" button. The necessary code for the .htaccess file is generated for you.
Practical Action is an international non-governmental organisation (NGO) that uses technology to challenge poverty in developing countries. Practical Action finds out what people are doing and helps them to do it better.