Anyway, below is what I've gathered so far. Feel free to share your knowledge in the comments regarding other resources you think others should know about.
Generally useful resources:
-Earth911: http://www.earth911.com/
-TerraCycle: http://www.terracycle.com/
-USAgain: http://www.usagain.com/
-Zero Waste Home: http://www.zerowastehome.com/
More specific resources:
-Bras: http://www.brarecycling.com/
-Brita Water Filters: https://www.preserveproducts.com/recycle/partners/204/brita
-Bulbs, Batteries, and Electronics: http://www.wm.com/residential/recycle-by-mail.jsp
-CDs and DVDs: http://www.cdrecyclingcenter.org/
-Corks: http://recork.org/
-Crayons: http://crazycrayons.com/recycle_program.html
-Greeting Cards: https://stjudesranch.org/about-us/recycled-card-program/
-Holiday Lights: http://blog.homedepot.com/save-on-led-christmas-lights-when-you-recycle-your-incandescent-lights-2/
-Ink/Toner Cartridges: http://www.staples.com/sbd/cre/marketing/easy-on-the-planet/recycling-and-eco-services.html
-Keys: http://keyforhope.org/what-we-do/
-Legos: http://www.brickrecycler.com/
-MAC Cosmetics: https://www.maccosmetics.com/giving_back/back_to_mac.tmpl
-Motor Oil that's been used: https://www.jiffylube.com/resource-center/a-second-life-for-your-used-motor-oil
-Pantyhose: http://www.nononsense.com/pantyhose-recycling.htm
-Pens and other writing utensils: http://www.penguyart.com/
-Running Shoes: http://www.nike.com/us/en_us/c/better-world/reuse-a-shoe
-Shoes: https://soles4souls.org/get-involved/give-shoes/
-Silicone Sex Toys: http://www.comeasyouare.com/sex-toy-recycling/
-Technology-related:
- http://www.greendisk.com/
- http://www.staples.com/sbd/cre/marketing/easy-on-the-planet/recycling-and-eco-services.html
-Unusable clothes/fabrics such as old undergarments (Bras/Panties/Boxers): http://www.usagain.com/
St. Louis, MO specific resources:
-Craft Supplies: http://www.upxchange.com/
Green bonus:
-Reducing "junk mail": https://www.ag.nd.gov/Brochures/FactSheet/JunkMail.pdf