This is a link to the online Lonely Planet travel guide about Eritrea. The travel information about Eritrea on their site is organized in the same manner as the Lonely Planet books, but do not expect the same indepth information. For that you will have to buy the book. This online destination guide offers the following information about Eritrea: Weather, Health & Safety, Time & Place, Crossing Borders, People & Society and Culture & History. They also offer a set travel links to continue your exploration of this country.
Very informative, no-nonsense travel guide about Eritrea 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 Eritrea, health and safety, respect and contact. For official travel advice, always check the travel advice from your own government.
WTG provides detailed travel information and articles about Eritrea. In the left menu you will find guides sorted by theme and with the menu on the right side provides the table of contents for Eritrea: overview, passport and visa, money, health, accommodation, going out, getting around, climate, map and images, travel advice and more. You can also create a miniguide that you can print.
World66 is a nice user generated travel guide made by travelers. Every part of the travel guide can be edited directly by clicking the  button. The guide about Eritrea contains information about the following travel topics: general information, map, history, practical info, economy, health, people, books and a photo gallery.
Excellent guide to Asmara by Hans van der Splinter. The guide provides information about public buildings, markets, theaters, shops, transport, bars, embassies and a lot more. Every article is supported by nice pictures and practical tips.