Dreamwidth Thread Tracker by Grub Grub

This adds a button next to the date in Gmail emails, which adds links to roleplay threads in a to-do list. It pulls your container tags and lets you choose which container it opens in, but default it will open in whichever tag you are in at the time.

As of version 4, it will add a button next to the (link) on a DW page. If you're in a container tab it will add it to the related list. If you're not, it will add it to the Default list.