First off, most TLD domain name extensions don't carry more weight than the others. The only reason the .gov, .mil, and .edu tend to have more links is because they are older and have a higher tendancy to link to each other in general. For example, in educational circles, it is common in papers to cite a source via linking. Thus, .edu domains tend to get links from each other much in the same way that blogs to. If you are buying a domain buy the .com whenever possible. The reason is type-in traffic. If you own the .com, you are likely to get free type in traffic without even google's help. For example: cars.com, sex.com, etc... get millions of visits a month just by owning the .com, even if they don't rank in Google. Of course, owning the .com for you keyword makes you look like the authority for that area just because nobody else can own the .com but you. Thus, you look more relevant. The .net and .org extensions are fine, but .com is where it's at. Also, don't be fooled by the .biz, .info., .tv, .ws, .us, or .me domain names. For various reasons, they just don't rank as well. Those domains tend to be either spam, or non U.S. related domains because a few of them like .ws, .tv, and .me are actually country code domains, so they don't even look like U.S. sites. In short, buy the .com. You'll be happy you did.