Building Firefox is a big endeavor. There are many teams and projects covering initiatives, maintenance, bug fixing, triage, localization, support, understanding feedback, marketing, communication, releasing, supporting infrastructure, crash analysis, and a bazillion other activities all to build a family of browsers and applications.
Teams and projects aren't static. People move around as priorities change and the landscape shifts and projects complete or are scuttled.
Sometimes projects get started up with a single person. Sometimes all the people except one move off a project. Sometimes we find ourselves working alone, in a basement office, with only a stapler equivalent to keep us company.
We are the soloists. You wouldn't believe the list of things we work on. Alone.
Where to find soloists: IRC, Slack
There's an IRC channel
There's also a Slack channel
#soloists on the Mozilla Slack .
These two places (and whatever other places soloists want to hang out at) are places where we can:
find some solace from the weary drudgery of being alone on their projects for days on end
ask for help
bounce ideas off each other
vent frustrations in a friendly forgiving place
get advice on dealing with things like code reviews and how to go on vacation
get recognition for a job well done
and a variety of other things that alleviate many of the problems we have as soloists.
Stickers at the All Hands!
Over the last month or so, we spent some time figuring out
stickers because we like stickers and you like stickers and everyone likes
They look like this:
They're 2" by 2" and round. They're warm to the touch. They make you want to climb things. By yourself. Alone. With appropriate safety gear. 
If you're a soloist, come find one of us and get a sticker. Also, consider joining soloist channels.
If you support soloists, come find one of us and get a sticker. Ask us about the things we're working on. We may be solo, but we're working on real projects that almost certainly affect you. As a group, we did great things in the last 6 months. Alone. So alone.