Having had my site spam-botted to distraction I first stopped registration and then started to look for a good captcha. Many of them need you to hack core file - way outside my comfort level. But although this is good, you need to look around for dummy-proof instructions.

I'll save you some time.

To enable captcha on registration, you need to download three extensions - SecureForm plugin, AUserManager component and ALogin module. Use the AUser Manager to configure the captcha you want (eg. registration)under Parameters. Other options are available if you want them. Enable the ALogin module and disable the one that comes with Joomla. You won't notice any difference between the two but the ALogin one takes you to the registration that requires the captcha.

Easy when you know how! It's the only thing that stopped me marking this "Excellent".

Very simple to install (always a plus point for me) and it has better image quality than some other galleries I tried. It really made the difference to my site, changing it from a static looking frontpage to a real attention grabber. My only quibble is that, with a random selection, it always seems to start with the same picture.

This generates a fantastic tag cloud which links to your search, making it not only user friendly but effective, too. The search returns a short sentence containing the tagged word so your user can decide which article is the most relevant. You can add or exclude as many words as you wish so you generate the cloud you want. My one criticism is that every time I go back into configuration, I manage to delete my list of blacklisted words and have to do them again. More likely to be me than the component, no doubt.

This is a really, really easy component to install and use. I had a few issues with it on my hosted site where I could not make thumbnails but Jan was incredibly helpful and, although I could not solve the thumbs problem, I found a workaround and now the site looks fantastic.
All credit to Jan for his swift help.