What is a good looking boot than can actually handle rain, sleet or snow?

Best boots in the, bar none. White's Boots - Custom made in Spokane Wa. - http://www.whitesboots.com/.

Many varieties to select from.

I'm not normally a fan of boots, but i bought a pair of Timberland's Chelsea Boots and they worked perfectly in the wet not terribly cold winters of Seattle. They look good enough to wear out (I have the Torrance, but Mt. Washington is good looking too) since they're not clunky and don't look like you're off to shovel hay or hike a mountain.

The Ecco Berlin Gortex boot is probably the most comfortable shoe I've ever owned. It's waterproof, has enough of a texture on the sole to handle some snow and ice, and looks perfectly appropriate with a suit.
Ecco Berlin Boot

Chris...right on. I never buy boots with thinsulate or anything like that. I'm a huge boot fan, and I always go with "Red Wings" or "Chippewas". Both brands capture timeless American style, while giving you serious ankle support, great traction and warmth for the winter months...Rugged leather boots are also a great way to beef up your pea coats, thick sweaters and chords and bring a little ruggedness into your city swagger...

They look great with denim, khakis and wool, and depending on the style they even work with a winter suit (even though I'd suggest having shoes to change into once comfortably seated in the office...

(they can also make you that little bit taller...which is great for your confidence...)

Agree with the Chippewas. I wear these in Jackson Hole every year, you can take them from the snow to dinner. They are waterproof, warm, easy to get on/off and look great.

http://www.chippewaboots.com/boots/country/25240

North Face Chilkats

I got a pair from Timberland Boot Company TBC is quite different from the regular Timberland line we all know. It's a nice blend of rough and refined.

Most of their boots if I'm not mistaken are made of oiled leather and wear incredibly well in the snow/sleet. The pair of Tackheads I got last year miraculously never got salt stains on them!?

I wear them in and around the suburbs and city so they get a good amount of use and have seen many puddles in the winter. The only downside is that they are a bit hard to find in retailers.

Vasque Sundowner

Classic Styling, Vibram sole, comfortable as hell. This boot has looked good for decades.

I definitely second the recommendation for Blundstone boots (http://www.blundstone.com/). I faced this exact problem when I was living in Ottawa, Canada for a few months last year in the depths of one of the coldest winters on record. I got through the entire winter, snow, ice, slush puddles and all, with a pair of these (unlined) boots and a nice thick pair of socks. They are indestructible, grip the ground well, and have a sleek look you can definitely dress up if called for.

i've got a pair of redwing gt's that can handle rough weather but my go to pair are bean boots by ll bean. i love how they look and i don't have to worry about ruining them.

Timberland boots are the best.

Most of the suggestions posted are for boots which I would not wear for a business casual function. I'm also not sure where the enthusiasm for Timberland comes from. Save those for your high school reunion.

If business casual isn't a requirement, invest in a pair of "Wolverine 1,000 Mile boots": http://www.wolverine.com/us/1000mile/ A welted boot which is cleaned and polished regularly will manage well over 1,000 miles.

If business casual is a requirement, the "Allen Edmonds Calhoun chukka": http://www.allenedmonds.com/aeonline/product_6490517_1_40000000001_-1?categoryId=122702&top_category=120552 looks great with everything from a suit to your best denim. I regularly wear mine on slush covered streets or in the rain to work. Clean them with a good leather conditioner and apply a polish cream regularly and they'll look new for years. Additionally, when the soles start to look worn, the recrafting option means you'll only be out $80 rather than the cost of a new pair of boots.

I cannot recommend LL Bean's Katahdin Iron Work's boots made for them by Chippewa boot company in Texas.

http://www.llbean.com/webapp/wcs/stores/servlet/CategoryDisplay?categoryId=57044&storeId=1&catalogId=1&langId=-1&from=SR&feat=sr

I bought them back in October when I went to the LL Bean store in Maine for the first time.

This week it finally got crappy out here in Chicago, with snow, ice, and slush.

As of day 3 these are the most comfortable shoes I own, and I completely LOVE THEM. Completely comfortable, warm (with a thicker pair of socks), dry, and good tread for slippery surfaces. They are fine in my office, but there is also an "engineer" variant of the boot that might be more appropriate if you feel the need to dress up more.

any well made boot with a nikwax treatment once a season will stay dry enough to handle most anything, save prolonged periods in standing water. if you do a lot of that, look for a gore-tex boot.
just be aware that the wax can darken certain leather colors.

Check out Sorel boots. They are made to be tough and warm. I swear by them!