Halogen Light Bulbs ROI
If you can't stand CFLs (even if you've given the newest generation an honest try), you need something with very smooth dimming or that can tolerate rapid switching, or if you want to totally avoid any mercury (such as in a baby's room), you may want to consider halogens. A halogen light bulb is an incandescent with some added technology, namely presence of a halogen element from the periodic table and a quartz envelope around the inner chamber, to sustain the higher temperatures they operate through.
In past decades, halogens were mostly available for specialized uses, such as in car headlights and in track lights and torchieres, and they had dedicated pin bases. However, over the past few years, manufacturers have been churning out "hybrid" bulbs that use halogen technology in familiar bulb shapes that can be "screwed in" to standard sockets. Halogens are typically 10-40% more efficient than incandescents, they can be switched and dimmed as much as you want, and they give off the soft, yellow light we are used to.
A typical example is the Philips Halogena Energy-Saver 40-Watt bulb (pictured) for general home use. A two-pack costs as little as $10 at some big box home improvement stores ($17 for two bulbs at amazon.com), and is designed to replace a standard 60 watt incandescent. So if we use our formula from above, we see that using one for six hours a day would give us 40 watts x 6 hours x 365 = 87.6 kWh. At 12 cents, that's $10.50 a year to use. That saves $5.50 a year versus an incandescent. At a retail price of $5 for the bulb, it's going to take a little less than a year to pay back (because we have to subtract the $1.50 a year for the cost of two incandescent bulbs. Philips says the Halogena lasts for an average of 3,000 hours, which is roughly a year and a half for our use, or three times that of the regular incandescent.