Before I forget about this. Here's an updated version with most links working with the new forum. Cheers
If you are a modder with questions about how to go about making your mod, please try the Modding Q&A forum.
If you have questions about mods, mod installations, or mod ideas, please try the General Mod Discussion forum.
Multimedia
Seifer's Multimedia Series #2 - Creativity in Photoshop (Seifer)
Seifer's Multimedia Series #4 - Sound Compression Advice (Seifer)
Diablo II Animation Extraction (Seifer)
How to add new movies to a mod (SConrad)
Music in Mods (Idobek)
Voice Recording for Mods (Berelinde [plus links])
new: Tutorial (and library): Universal portrait packs (EE compatible) Photoshop & WeiDU
NPC
Adding voice to your mod (SConrad)
So You're Going to Write a Romance (David Gaider)
WEIGHTs in BG2 Dialogues (JCompton)
Writing dialogue in .d for REAL beginners (Kulyok)
Tree of Life Gut-Check (Grim Squeaker)
The Looping Branch Lovetalk Technique (JCompton)
Very Long NPC Creation Guide (theacefes)
Writing a detailed Anomen romance conflict for an engaged PC (jastey)
How to ensure your banters always run when you want them to (Kulyok)
Some Tips and Tricks on Creating D-files (Domi)
How to avoid duplication in your dialogue files (Kulyok)
Spawning Joinable BG2 NPCs in a Seamless Fashion (CamDawg)
Journal Entries for Dummies (Grim Squeaker)
new: SoD NPC Modding Tutorials (jastey)
BGEE NPC Modding Tutorial (Google Docs, PDF-download)
WeiDU
Using WeiDU GROUPs to organize your mod (CamDawg)
WeiDU SUBCOMPONENTs (CamDawg)
Kits
BG2 Kit Creation: Limitations of the Engine (1) (CamDawg)
BG2 Kit Creation: Game Files Involved (2) (CamDawg)
BG2 Kit Creation: Installing with WeiDU (3) (CamDawg)
BG2 Kit Creation: Additional WeiDU Functions (4) (CamDawg)
Porting Mods
Porting WeiDU Mods to Mac OS Xs (CamDawg)
Porting WeiDU mods to Linux (the_bigg)
Misc.
BG1 Coding (jastey)
BG1 Trigger Simulations (Zed Nocear)
How to gather clues when debugging stuttering (the_bigg)
The uses and abuses of secondary types (Nythrun)
shs: Area Modding Macros and Tutorials (Qwinn)
Coding scripts in SSL: some lessons (DavidW)
Windows Vista and IE games (berelinde)
IWD engine: dialogue coding (Kulyok)
Crossing the Great Divide: Modding for Tutu and BGT (cmorgan)
Dialog Files and How They Are Referenced (templates) (cmorgan)
Explaining Creature Patching by .tp2: An introduction (Nythrun)
BG2: Creating Forced Encounters (Andyr)
Easy Item Dialogs (Smoketest)
Modder How-to: Integrating Your Mod with DR's Spell System (CamDawg)
IWD2: Modders guide to Spells (Da Rock)
Multiple BG2 Installations (CamDawg)
Changing Class/Race/Kit Restrictions with WeiDU (CamDawg)
Adding a trigger to an existing map via WeiDU (Creepin)
Igi's DLTCEP setup tutorial (igi)
Upgradeable items with Cespenar and Cromwell (CamDawg)
Adding new areas and links to worldmap (SConrad)
Tutorial: Item Patching (CamDawg)
Resurrecting "deleted" Spells in BG1 (Smoketest)
Changing Priest/Mage Spells to Innates on the Fly (CamDawg)
BUT_ONLY_IF_IT_CHANGES (Idobek)
shs: Cuv's Area Making Class Tutorial (Cuv)
shs: Online Area Making Seminar (Cuv)
youtube: General Camera angle info for completely new areas 3D->2D creation (3DSMax/Blender etc.) (Daring Dino)
Otherwise interesting new/pinned topics:
IESDP (Infinity Engine Structures Description Project) G3 Community
Install order online list for modders & maintainers (AL|EN & Community)
pocketplane: Complete Scripting Guide (SimDing0)
Cheat Keys (like CTRL+1) & Console Commands BG1, BG2, IWD, IWD2, BG1EE & BG2EE
Software Tools index
new: A Basic Modder's Guide to Git and Github (CamDawg)
Links to other tutorials/communities
IE Modding tutorials are also available at other sites, including:
Official Beamdog forums (for IE Enhanced Edition Mods) General, UI, PST:EE, BG:EE, BG2:EE, IWD:EE
WeiDU README (weidu.org)
WeiDU Forum (pocketplane)
General Tutorials (blackwyrmlair website)
General Tutorials (blackwyrmlair.net forum)
Graphics-related tutorials (blackwyrmlair.net forum)
Old TeamBG Tutorials (teambg.eu via archive.org)
General Tutorials (SHS, Tutorial-Index )
IE Modding forums (SHS)
PocketplainGroup (PPG) Tutorials (pocketplane.net)
baldursgatemods.com (old forum, domain was TeamBG.CoM )
Sorcerer's Place - Download Archive
Simpilot Tutorial Website (simpilot.net, Mirror: http://web.archive.org/web/20150511131433/http://www.simpilot.net/~sc/dltcep/ )
chosenofmystra.net forums (archive.org)
CBisson's Adding X to an Area with WeiDU TP2 Templates (links dead) (see also this & this)
PPG: PPG Infinity Engine Modlist a comprehensive list of tutorials & ressources
http://www.rpgdungeon.net (archive.org, lot of links dead)
gameapps.com - IE Tutorial Website by Theo