Web Form Captchas - any recommendations?

[Famous Graham]

Getting flooded with bots using our webforms on our company site so I need to put in one of the image verification doobreys.

Ideally hosted locally due to availability issues, but the kicker is, I don't have access to the PHP templates our CMS runs off (legacy situation that would be a pain to resolve seeing as I'm developing a new independent site anyway)

I can host php on our site though and call the script as the action for the form and the url of the image obviously.

So, anyone recommend any particular one? There's oodles out there.

[Plotloss]

I use this one, find it very good.

www.tectite.com/formmailpage.php

[Famous Graham]

Nice one Plotty - that does indeed look very comprehensive, I'll have a play