It can be worth, but it takes more knowledge / experience to invest in .org or .tv than to com. This is because .com is more general, while .org and .tv are very specific markets than one needs to understand.
Watch listen to the news for new slang or technology terms. If you buy all names related to these terms it will be just be reinvented so pick up the best of the terms. Just listen for new trends in words perhaps add keyword free with it or synonyms and antonyms with your new found slang or word.