These are websites that provide additional information and resources on all thing related to board games.
This is undoubtedly the premier board game resource website. The database is huge as it tries to catalog every board game ever published. The content is mainly user driven but this is the place to go if you want to check out a game, read reviews or just stare at pretty photos.
Like BGG, this blog features game reviews and opinions from veteran gamers I respect. Spearheaded by Dale Yu, a boardgame designer and enthusiast, this site features a dozen or so guest writers that contributes opinions and reviews. I particular love how to rate games and have partially adopted some of their ideas for rating games. Be warned though, the site features mainly Euro gamers with little to no Kickstarter or Fantasy Flight presence.
Bruno Faidutti is a well-known French designer best known for Citadels. Citadels have been around for a long time and is an evergreen title. I occasionally visit this site for insightful comments on the current state of board game affairs as well as cool gems and nuggets of wisdom. Bruno also shares some of his designer diaries which is always revealing and thought provoking.
Reiner Knizia is one of my favorite game designers. His games are usually simple, but features subtle depths that come out only when players interact. His games allow a 6 year old child, a 35 year old father and a 70 year old grandfather to engage and bond over a single game without any one getting bored. That is no simple feat. His productivity is astounding and his games continues to get reprinted every year globally by different publishers. See for yourself.