Don't you hate it when you’re trying to describe something but don't know the name for it? As a writer, this really bugs me. The other night I was tying to find out what you call those pads that hold your glasses to your nose (they're called "nose pads" if must know) and stumbled across a really useful visual dictionary from the good people at Merriam-Webster. I haven't gone through their entire offering but it seems to be at least as good (maybe even slightly better) than my giant visual dictionary I've been refereeing to until I got too lazy to pick it up last night. And what's really cool is that they list the definitions to all the words on the bottom of the page.
One note when using visual dictionaries: Occasionally visual dictionaries use the technical word for or a part or piece of equipment instead of what the part is commonly referred to. If the word sounds to strange, ask someone who knows what it’s really called.
Check out Merriam-Webster's visual dictionary here.