I'd like to offer something like flash games on my site that come with a highscore table so that visitors can compete with each other, and I can offer prizes at the end of the week/month for high scorers.
Does anyone know where I can find such things? Haven't had any luck googling.
If you can write or find the flash games, then a little php or perl scripting should be all that is required to save the high-scores. You should be aware, however, that a hacker would find it easy to add fake scores.
A Hacker could find it easy to send false scores if he/she wanted to by just making their own form and submitting it to your site.
You could check the referrer on all form submissions to ensure it was from your domain and refuse it otherwise.
Also you could munge the data you are sending so they would not know in what format they would need to send it in.
It could still be hackable, but this would prevent the most common ways to send false form data. You most likely find it difficult to find this pre-written so you would need to get someone to help you with that.