LDS Lessons and Talks
LDS Church Manuals
If you're looking for this year's manuals than check out this new article, "LDS Church Manuals" listing all the available manuals and resources from LDS.org including instructions on how to find them!
Teacher Training: Preparation Handouts
These three articles go over three different areas of preparation including: spiritual preparation, lesson preparation, and room preparation.
LDS Distribution Center
The LDS Distribution Center has tons of resources that are sold at cost price. There's even free shipping within the US, Canada, and the Caribbean.