This is the best English wiki: demonssouls.wikidot.com

Many players have contributed to the Wikidot version since the Japanese and Chinese versions of Demon's Souls were released in February 2009. I've used it many times and found the information to be very reliable. I've even contributed to a it a few times (and yes, it's still reliable :p).

This is the official wiki, but it's lousy: demons-souls.com/wiki

Here's another lousy one: demonssouls.wikia.com/wiki/Demons_Souls

If you can read Japanese, this website has lots of maps: www.geocities.jp/kouryakubo/ds

Thanks to DuneMan at GameFAQs (and my corrections), here are the direct links to maps on the Japanese website:

Tutorial: http://www.geocities.jp/kouryakubo/ds/chart/chart011.html

Nexus: http://www.geocities.jp/kouryakubo/ds/chart/chart012.html

1-1: http://www.geocities.jp/kouryakubo/ds/chart/chart021.html

1-2: http://www.geocities.jp/kouryakubo/ds/chart/chart031.html

1-3: http://www.geocities.jp/kouryakubo/ds/chart/chart041.html

1-4: http://www.geocities.jp/kouryakubo/ds/chart/chart051.html

2-1: http://www.geocities.jp/kouryakubo/ds/chart/chart022.html

2-2: http://www.geocities.jp/kouryakubo/ds/chart/chart032.html

2-3: http://www.geocities.jp/kouryakubo/ds/chart/chart042.html

3-1: http://www.geocities.jp/kouryakubo/ds/chart/chart023.html

3-2: http://www.geocities.jp/kouryakubo/ds/chart/chart033.html

3-3: http://www.geocities.jp/kouryakubo/ds/chart/chart043.html

4-1: http://www.geocities.jp/kouryakubo/ds/chart/chart024.html

4-2: http://www.geocities.jp/kouryakubo/ds/chart/chart034.html

4-3: http://www.geocities.jp/kouryakubo/ds/chart/chart044.html

5-1: http://www.geocities.jp/kouryakubo/ds/chart/chart025.html

5-2: http://www.geocities.jp/kouryakubo/ds/chart/chart035.html

5-3: http://www.geocities.jp/kouryakubo/ds/chart/chart045.html

Final Area: http://www.geocities.jp/kouryakubo/ds/chart/chart061.html

Always used the wikidot.com, sometimes i feel like it was missing some information but at the end it's the best all around.

It'll be great to see more strategies, build, etc.

Any wiki is a work constantly in progress. Now that the N.A. edition is out, there should be more players contributing updates.

I hope so, it'll be great to see how other players will approach this game, and maybe we'll found an use for the Beast Demon Soul and other objects of unknown properties