I was going to suggest that you do a search on the forum, but I tried it myself first and realized that for whatever reason it is not turning up accurate results. There have been a fair number of posts on this subject on the kitchen forum as well as the bath forum. If you go to Google and use advanced search criteria (such as "concrete countertops" site:ths.gardenweb.com ) you'll find a number of the threads.

A few months ago I posted this:
"We have concrete countertops on the perimeter of our kitchen and leathered granite on the island; we also have concrete countertops on the wet bar. I extensively researched concrete countertops and my Asheville, NC based fabricator/installer before deciding to go with them.
IMHO, getting a good installer who really knows what he is doing and has a lot of experience is key to your ultimate satisfaction with concrete countertops --- perhaps more so than with about any other countertop material. The other key is getting a good sealer. Until recently, the concrete countertop sealers all seemed to have one problem or another --- either they looked plastic-y, they scratched badly, or they didn't provide adequate protection. A new sealer has come out in the past couple of years that seems to have solved all of these problems. I wish I could tell you the name of it, but unfortunately, I don't know it! All I know is that it is cured by a UV lamp. I tested samples by leaving a variety of products (red wine, mustard (usually hard to remove), lemon juice, ketchup, etc.) on a sample overnight. Nothing etched or stained the concrete. I was sold.

The countertops have now been installed for nine months and we have no cracks, scratches or stains on them. Admittedly, this is a weekend and vacation home so the countertops have not been used daily, but the countertops have not been babied. Mine is a working kitchen, so the countertops do get exposed to lots of messes. I actually find the concrete countertops as easy to keep clean as the leathered granite on the island. I use the same cleaner (Method for Granite) to clean both of them, although my concrete fabricator recommended a beeswax finish (too much trouble!).

You can get a lot of good information about concrete countertops at the link below. Just for the record, I have no affiliation with this group, whatsoever. There's also quite a few previous posts on the subject if you can get the GW Forum's search function to work correctly. Cheng's books are good if you intend to attempt this project yourself -- not something I recommend and definitely not a project not for the faint of heart.

Hope this helps."

We have now been in our new lake house almost one year and I'm still very happy with the concrete countertops. By the way, since I made the post above I have learned that our countertops were sealed with the UV sealer made by Surface 519. Here's a link for more information on it:
http://www.concretenetwork.com/products-sealer/solution-library/counter-uv.html

If you have concrete countertops professionally installed, they will not be any less expensive than other materials (e.g. granite, quartz, soapstone, etc.), and might even cost more. Some very handy people on this forum have fabricated their own - they saved a lot of money and most that I have seen photos of, look pretty good. I think the professionals might have better tools and know some tricks of the trade that will alleviate or prevent problems down the road (such as cracking and staining). But it all depends on how much money you have to spend and how much of a do-it-yourselfer you are.

Let me know if you have any other questions.

Here is a link that might be useful: Concrete countertop institute

Generally they are made locally by "studios" and start at around $100 a sq. ft. and go up from there. These are a premimum product.

We have Vetrazzo countertops which are recycled glass set in concrete matrix. I ditto the above comments about having an experienced installer do your work. Despite what our KD and we were told, our installation company wasn't experienced and made several mistakes including not waxing and sealing our countertops initially. Thankfully, we discovered this and paid to have another company come in and do this because the installation company refused to despite being shown on the Vetrazzo website that they should have. (Very long story made short here!)

Very curious to hear more about this uv sealer since we are using the pour and buff method for our counters and I believe it is a Cheng product...

I looked into concrete countertops when I was busy dreaming about a kitchen reno. That never happened, but the more I learned about concrete, the less I wanted them. The other posters have hit the nail on the head, according to what I learned: your countertops are only as good as the person making them. I didn't feel confident that I could find a highly qualified person to do them in my market (which tends to be a bit behind the times in trends so they are still very unusual here). Add to that the maintenance issues: sealing, etc. and I realized it wasn't for me. I get a red-wine ring on my counter every night. No biggie because they are laminate, but I just knew that I'm not the right person for concrete. I think they are absolutely beautiful counters, as are marble and soapstone, but they just aren't right for me personally.