* Web services (though see below)
* Infrastructure, such as Amazon's announcement today: https://news.ycombinator.com/item?id=18539539 and quite a few other things, like Chef's Habitat product, Boyant's linkerd2, Dropbox's core infrastructure, or System76's hardware flashing tooling
* Cryptocurrency stuff of various kinds
* Databases, such as PingCap's TiDB
* Operating systems, like Google's Fuchsia (This one is arguably not "production", but they are one of the largest employers of Rust programmers, and keep hiring... so maybe consider this, maybe don't.)
* Version Control systems, like Facebook's Mononoke, or the internals of mercurial itself, as well as things like Pijul
* Cryptography, in some cases working alongside C to slowly port things over
* Video games, mostly indie stuff, though some AAA studios have started to use Rust for various things, and a new studio, Embark, is going all-in
We have a partial list of companies that describe their usage here: https://www.rust-lang.org/en-US/friends.html
This year, we identified four areas we really wanted to improve Rust on:
* Embedded development
* Network services
* CLI tools
These are other common areas we see people wanting to use Rust in the near future, or areas where we could significantly improve Rust for that given case.
EDIT: I forgot to answer your other question
> Does it only outperform them, or is it also a pleasant language to use?
Performance is a key thing we hear from people in web development, but increasingly, it's also memory usage, both in amount and stability. Less memory means less money spent on servers, and steady usage makes scaling calcuations easier. For example, crates.io is a rust-based web application, and it uses about 30MB memory resident at all times, last I checked. That's very little. More serious systems use more, but often significantly less than the JVM.
I had no idea rust was that prevalent