Michelin has excellent maps of Europe. The printed maps I have don't show the town the country house is in. However, their online maps are quite detailed; I can even get directions from my Niece's house (in Prague) to the country house!
Mapquest's European maps only cover a few NATO-like countries.
Google maps uses TeleAtlas data (well, in CR at least).
MapPoint uses NavTeq data in the US.
Not all maps are available at all scales, and sometimes the map and map etail level of a particular type of map changes with the scale. All-in-all, though, quite useful.
One particular thing to note is that map moves and function changes go back to the server to generate a new page. This is quite handy -- you can reverse in the browser history list to find someplace you where, instead of having to scroll the map.
Here are places to get good maps and atlases from. I find it difficult to purchase properly detailed maps of Europe in the US.
Some of the best maps of the Czech Republic that I have seen are available from the local petro companies. They are large scale, and show all the roads, filling stations ... even the competition's filling stations! They are often high quality and large scale, and are a joy to drive and navigate with. I would like to see maps as good as those of locations in the US.
Rough Guides are a good source of quality generic maps.
Maps to Anywhere also carries travel, language, and other difficult to locate products.
Omnimap caries a wide variety of cartographic products, including terrain and resource and other specialty information.
Stanford's Books and Maps is in the UK, and has a nice browsing system to locate maps of interest.