If I want to travel from point A to point B without the aid of a powertrain, I usually mull through a few options depending on the weather and terrain. I don't claim my list complete, but short of including draft animals, no one would claim that we have an abundance of human-powered alternatives to choose from. As you will see, not all these provide a practical means of commuting, unless, as you will notice, the proverbial hell freezes over.
Mountain Bike:
The old reliable that operates decently under just about any climactic conditions. I bought this one custom-made in 1984 and still use it after it remained in cold storage with a frozen seat-post for several years. This one has a shorter wheel-base than my other mountain bike which gives it a squirrelly feel and a more upright ride. Notice the snow on the tires. At one point long ago, I tried an experiment and I covered the tire treads with an array of short machine screws to gain better traction on ice. Unfortunately, I chose screws a wee bit too long and I made it a few yards before the tires deflated with dozens of puncture marks. Duh. Lesson: You may fall on ice. Deal with it.
Road Bike:
I will pass on the mountain bike without hesitation if I have good road biking conditions. The choice really comes down to efficiency; I will break less of a sweat on a road bike any day. The day-to-day trade-off remains dealing with tire flats. Keep the tires inflated to avoid pinch flats and don't skimp on quality tires and tubes. Pictured: a Bridgestone RB-2 purchased for $99.
I don't think I would ever use a recumbent bicycle; I would much rather loom over a car driver than sit at the same elevation as road-kill. Never mind the differences in mass, road bikers and bike messengers will become the Alpha males of the city streets once all the SUV's disappear. Height always wins.
Hypno Skates:
Hypno makes inline roller blades with a detachable chassis. I would recommend these for any relatively smooth pavement without a lot of steep downhills. I have a long history with in-line skates, having purchased the original RollerBlades not long after local hockey playing brothers first brought these to market in the early 1980's. I can remember naively skating around university hallways on RollerBlades before the big crackdown -
"NO SKATES ALLOWED!". The Hypno Skates bring back some of that freedom. As for advice, resist the temptation to use the heel brakes; practice until you get good at doing slalom/pivot stops.
Cross-Country Skis:
No lie: I have actually commuted on cross-country skies, about 7 miles each way. I started with classical skis, but have used skate skis almost exclusively the last dozen or so years. For skate skis, you need specific snow crust conditions to get the best efficiency and mobility. Basically you have to wait for a thick blanket of snow, followed by a partial meltdown, and topped off by a hard freeze. If you have this and happen to live on a large connected maze of lakes or safely frozen rivers, consider yourself lucky. Unlike England, we can't count on right-of-way pasture lands to navigate. And, conversely, England can't count on snow. Rats, Utopia does not exist. One other possibility, you can follow rural snowmobile trails or use partially plowed roads. Unfortunately, these will become your "rock skis" after this point. Lastly, consider a move to Norway.
Hypno Skates (ice):
Kind of bizarre, but I have ice skating attachments for my Hypno skate boots. Occasionally one can find a considerate lakeshore homeowner who will Zamboni a skating lane around the perimeter of a lake. Many people from warmer climates don't realize this, but the number of transportation routes increases in the winter. Commuters that had to make quite a detour to cross a river during the warmer months get to use an ice crossing for a few months in the winter. A narrow window of opportunity (and safety) to say the least.
Clap Ice Skates: These speed skates use cross-country ski bindings and boots. A European idea, I bought these from REI a few years ago; I don't think they caught on but they do work amazingly well. As a word of advice, unless you live on a series of canals ala Amsterdam, don't depend on the consistency of lake ice; prepare to take a number of "headers". In the last few years, we haven't had as much snow, so I have gotten used to unexpectedly flying through the air hat first. 
Kayak:
This narrowly beats a canoe if you happen to have a commute that follows a slow-moving creek or river or a long lake. Kind of a rare occurrence, I know, but what the heck.
Finally, I can't forget to mention the backup strategies: walk, jog, or run. Advice: Start by crawling, and you will soon get the hang of it, usually by the age of two.