We have gone through parish books, censuses, school registers or maps, but there are many more online sources for Czech history. One of these sources is website Fotohistorie.cz which offers old postcards and photos from all around the Czech Republic. It's not a source covering every village and every town but it can provide very nice postcards for many Czech towns and villages.
Main page of the Fotohistorie.cz project
The website is available in Czech only so I decided to prepare a short guide to it so you are able to find out if "your" village is covered. There is a list of Czech regions in left menu, beginning with the capital Prague (Praha) and then all other regions listed. When you click on the region (sometimes you have to click twice before the list appears), list of district will appear as well as map zoomed in to the region (as shown on example of Liberecký kraj below).
When you click on district (Okres) name, you'll get a list of localities which have some photo published on the website - there is number of photos included in the brackets next to each name:
You can choose the village by clicking on it - I chose Ferdinandov in Liberecký kraj and district Liberec as an example. Village page will appear and you'll see available photos, the oldest one loaded under a window with thumbnails of all photos.
You can then click on the photo and new window (or tab) with full resolution of the photo/postcard will appear.
You can also use map on address http://fotohistorie.cz/Mapa.aspx - when you zoom in the area which is interesting for you, you'll see which villages have old photos or postcards available (marked with orange flag) and which not.
Happy photo-hunting! Let me know if you found your ancestral villages there. :)