Matador, a worldwide network of travellers, writers and photographers. Not only is it jammed packed with advice and guides, but there's lots of stories and articles to whet the appetite; I love the fact the pieces are short and often very funny. If you need to kill time at work, this is a great site to visit.
It's also a great way to get writing on the web (there's a very active online community) and meet other like-minded travellers. I recently came across this piece ('top 10 Mexican foods to try') by one of the contributing editors, Sarah Menkedick. Sarah's based in Oaxaca (lucky her) and also has her own blog here.