Hi Andy.
I noticed on your homepage you are making use of two images for the hover effect (the van).
This took a bit of time for me to load the first time I hovered over the image.
You can do this with background images in CSS instead, and only use one image (you can do it with pure CSS if you disregard IE6 otherwise it's quite simple to do it with JS).
Here is a quick howto for doing it:
litetest.com/Knowledgebase.aspx/HoverOverImages
On your registration form, only two fields actually mention the validation error (email, saying "enter a valid email", and password saying "Must be at least 8 characters long").
The banner link on your left don't open in a new window which drives traffic away from your site.
Sorry, I start giving you website feedback here in the intruduction (old habits!)
I just had a new boiler installed about 1 hour ago! He was talking about website so I should have mentioned yours to him, I will do if I speak to him in the future!
It's very nice that you provide a free service like this, I like it!
If you are interested in website feedback do let me know, I got a few thoughts for you.