About.com: Decorating and design section from About.com. Lots of articles and resources, much of it written for a more American market, but lots of useful tips nonetheless.
BBC Homes Design site: Hundreds of ideas and advice tips. Lots of pictures of projects. Very informative and useful site. You can even look at the plans from 'Changing Rooms'.
Blinds UK: UK retailer offering quality window blinds for home decor and sun protection.
Crown Paints: Not a design site in itself but from their website you can download and install a nifty little tool they've created called the colour creator - allows you to add photos of your house and change the colour scheme.
Dulux Paint: Check out paint colours, get advice on which colours to use, and store ideas in your own personal online scrapbook.
GetDecorating.com: huge decorating portal for members. Mainly aimed at the American market but there are thousands of pictures for inspiration.
iVillage: The home and food section at iVillage.com contains lots of ideas for redesigning your home.
UKTV Style: Website of the lifestyle tv channel. Lots of inspirational ideas on how to transform your home.