phpflashcards.com is a site designed to help new and experienced PHP developers hone their skills for certification exams. The site:
- Uses AJax
- Is new: there only few questions and many categories are there with 0 question
- In Beta: needs to be evolved. You can help adding questions and answers. It has wiki-like features so that users can submit and edit questions and answers.

Here are some questions from the site:
- If a cookie is set with JavaScript can it be accessed with $_COOKIE?
- What function is CASE_LOWER used with?
- Which format character represents an RFC 2822 date format?
- What is the difference between time() and date('U');

Check it out: phpflashcards.com