Atmos Energy (NYSE: ATO) is the nation’s largest all-gas utility. Atmos isn’t exactly a sexy business, but the reliable cash flow provides some great dividends — a yield of 4.7% at current valuations and payouts since 1984. My price charts indicate that Atmos has been consolidating between $26 and $30 for most of 2010. As of this writing, ATO shares are right smack in the middle of that range, and that means it’s a good buying opportunity before the next leg up. With a solid business and great balance sheet, Atmos is a very wise long-term dividend investment right now.