One-word Syndrome

What's funny about having lived in Sweden for two years is that I have started to confuse myself when it comes to compound words. Should keychain be one word or two? What about bookstore? And icecream? Or railroadstation? Hmmm, perhaps a homeimprovementproject? Well, the Swedish language tends to combine two words into one and even this nitpicking editor here seems to have been infected with the one-word syndrome unconsciously. Help! I need some brainrinsing!