The Ethiopian Tourism is an official travel guide by the tourism commission of Ethiopia. Look here for information about: Addis Ababa, natural attractions, cultural attractions, historical attractions and archeological attractions.
The online Lonely Planet Destination Guide about Ethiopia offers up to date travel information. This online travel guide offers broad information on several topics, but is not as informative as the books about Ethiopia. You can order the Lonely Planet book online if you like the information they offer. Apart from background information about Ethiopia, like info about culture, history and transport, you will also find an image gallery, travel forum (Thorn Tree Forum), maps, postcards and a nice set of travel links.
Very informative, no-nonsense travel guide about Ethiopia by Wikitravel and a good place to start exploring your travel destination. The information is divided into the following topics: regions, cities, entry requirements, getting out, languages, eating, drinking and sleeping, learning and working in Ethiopia, health and safety, respect and contact. For official travel advice, always check the travel advice from your own government.
WTG has many travel guides about all countries in the world. The guide about Ethiopia provides information and articles for tourists. On the left the guides are sorted by theme. The menu on the right side provides the table of contents for Ethiopia: overview, adresses, money, duty free, public holidays, accommodation, going out, map, images and more. You can also create a miniguide that you can print.
The World66 guide about Ethiopia is an user generated guide. You can help building this guide by clicking on the  button. This Ethiopia guide provides information about: general information, map, history, practical info, economy, health, people, books and a photo gallery.
WordTravels is a site with many comprehensive country guides and city guides. This guide about Ethiopia contains the following travel topics: introduction, facts, health, contact, airports, map, weather, currency, visa, photos and flights. The region, activity and city guides for Ethiopia can be found in the menu on the left.