Symbian Links 

Telegram Groups

Software (Symbian S^3, Anna, Belle):

Symbian Development Tools (manuals, compilers, development tools, QT installers etc.):

Symbian Zone VK Group (Software and Discussions)

Delight CFW Firmware

Nokia Firmwares

All About Symbian
(also accessible through RSS apps or podcast)

Archives of Nokia Maps

The "must have" independent 3rd party Stores for Symbian ^3/Anna/Belle devices (Trusted Resources)

Entire collection of SIStore archive (Trusted Resource) 


Before you upload apps, check the SIStore repo if the app is already available. If it isn’t available or it is a newer version or ovi-signed version you can upload it.

You can download/purchase some apps directly from developers here:

Kutegram - Telegram Client for Symbian

Other Resources

Old N8FunClub Apps (not trusted anymore)

Former Nokia/Opera Store:

You can also check the following sites (but proceed cautiously):

Maps and other resources:

Official collection of music, sounds and ringtones included in various Nokia and Lumia phones over the years can be accessed here:

Guides to hack your Symbian devices can be found here:

And here:

For any developers interested in Symbian source code 

Finally, you can also join the Symbian community in facebook: