Expat Focus provides information and resources for expatriates for a large number of countries, including the Czech Republic. The website also host forums and blogs for expats.
Expats in Prague offers in-depth information for the expatriate community in Prague and beyond.
Prague Tourist Service is the official source of in-depth information about Prague.
Lonely Planet Worldguide provides a ton of useful travel information. Check out the Czech Republic section.
Rough Guides Destinations offers useful travel advice and information for most countries, including the Czech Republic.