Working 2nd shift w/a 40 mi rt commute means I cycle in the dark alot. My homeward leg takes between 1:15 and 1:30 depending on how I feel. The key is GOOD lighting and good tires. My lights are NR Trailrats w/a Universal taillight.
http://www.brandcycle.com (no shipping) Also, Planet Bike Superflash blinkies.
http://www.amazon.com (no shipping). Tires are Schwalbe Marathon Plus
http://www.biketiresdirect.com on all my commuters. The fail/safe commuter has Nu-teck airless.
http://www.nu-teck.com
A combination of thriftstore/yardsale finds, 70-90% off online sales(peformancebike.com, nashbar.com, bikeisland.com, universalcycles.com, bikepartsusa.com, lickbike.com, aebike.com) and biting the bullet on a few 'must have's' in terms of cold/wet weather gear(Lake winter road shoes, ip barrier jacket, j&G cyclewear raingear, Gordini Goretex gloves from campmor.com) makes for a very pleasant experience most nights. Having light failure means I learned the value of a back-up system and trying to 'scrimp' on cold weather gear taught me the value of quality.
We live near the Natchez Trace Parkway here in rural mid-Tn and the night rides are a joy. One might do 50 miles w/o seeing a car some nights. Knowing the terrain, your own limitations, potential hazzards, etc. can make night riding a pure pleasure. The only thing I worry about is startling a buck in musk who decides he doesn't want to run...it happened once during the day and I was fortunate to be on a 35 mph decent when he turned and chased for a few seconds...VERY scary.
People at work constantly remark about the dark, the cold, the wet, the distance, etc., etc. and I just smile and tell them if they would come with me just one time they'd 'get it'. There've been a few genuine queries about gear, logistics, time/distance, conditioning, but no one else has taken the plunge...yet. Out of 4000 people I'm the only cyclist-commuter and the security guards wave me in w/a look of bemused respect...I like that.
Just got my wife a Cygolite Night Rover w/2 6w halogens as she wants to ride after work and it's dark by the time she gets home. Seems like a good set-up for the money. The TRs are 10w halogen which is plenty for the speeds I ride...15-18 mph avg.
My night rides, though utilitarian, functional daily commutes are, also a part of my existance I've come to look forward to. I may go 3-5 legs home and see 2 other vehicles once I get off of the company property...life's good. The rides are getting better...I'm even doing a single speed 1 or 2 times per week. I could go on, but I think you all get the idea. The money I spend on gear I'll have for the rest of my life. The money I spend on gas lasts...maybe a month? Thinking about getting a trailer and going car-lite...but that's a different sub-forum and thread.
