Create a list of the best and most useful websites for interior design ideas, inspiration, and products.  The list should include at least 30 websites.  Focus on websites that provide design inspiration ideas, step-by-step instructions for DIY projects.  The list should also include a list of the best websites for purchasing furniture, home decor items, wall art, and wallpaper.  Don't include any websites that offer low-quality products like Wayfare.  Separate the list into categories, and for each listed item include a brief description of the website and why it is included on the list.  The goal is to have a useful reference guide.