Here you will find useful sites containing tools and resources for Simutrans.
Many of the resources below are created by fans. As with all things Simutrans-related, anything not released by the development team (the newest versions of the Simutrans engine/executable, and generally Pak64, which is the ****umed and official Simutrans graphics set) may not be kept up to date with the latest version.
The entire community is made up of volunteers; folks making these programs can't add the latest version until it is released, and even then, everyone has a 'real' life - updates are never immediate. But often, they are kept pretty well up-to-date. But you should make sure that they support the particular version of Simutrans you have downloaded.
Simutrans.com - Links
:arrow: http://www.simutrans.com/links.htm
(credits to Isaac for original text)
EDIT: Now all links are at www.simutrans.com.
I started a Simutrans group on Facebook:
http://www.facebook.com/group.php?gid=83052149546
I removed that huge list of sites. Now you can find (almost) everything by simutrans.com. :)
Plus, I'll add Simutrans' Facebook into Simutrans' sites list.