I started a notebook to keep track of all my ideas, that way I can tote it with me to the store and back and forth between the new house and old house. I took a bunch of plain white printer paper and 3-hole punched it. Whenever I find color schemes or magazine pictures I like, I cut them out and paste them in there. I also have some lined paper for notes, a plastic sheet protector to hold small things like paint chips, and a hole-punched two-pocket folder to hold other things.
Another way to keep track of your ideas is by using Kaboodle. Kaboodle is a website that lets you keep track of all your internet shopping finds.
You can create multiple lists, and even create sub-sections inside your lists. I have a list for "House" and inside that list I have sections for "Master Bedroom", "Kitchen", etc. Kaboodle has a handy button you can install on your browser toolbar. As you are surfing the net, if you come across something you want to save, you just click the "Add to Kaboodle" button on your toolbar and it adds it to your list.
One of the best things about Kaboodle is that it will also show you things other people have found that are similar to things you have saved in your list... it's a great way to get new ideas.