blandflakes uses Java
Pretty much everything - Java is reasonably fast, reasonably safe, and reasonably expressive. I wouldn't call it the best at any of those things. The real advantage to me is that the virtual machine is ubiquitous and many people can understand it. Since I have the most experience in this language, it's my tool of choice for most projects.
I've also been learning JavaFx so that I can build user interfaces without the web. I've started several single-page-application projects that worked, but felt like workarounds or hacks and would be better-served as self-contained applications.
denkbar.io uses Java
Do I really need to explain? Well to me, the most appealing factor in Java besides the unbelievable community and vast array of available libraries, is just the amount of effort that has been put in the modern JVM. Decades of optimization and improvements have lead to a terrific piece of technology. I admire the people contributed to that.
StackShare uses Markdown
We’re using Markdown parsers for Reviews, Blog Posts, and Stack Description (the text you’re reading right now). We’re using Bootstrap Markdown for content input (except for reviews) and RedCarpet for rendering in certain places.
WingTangWong uses Markdown
Markdown represents a highly portable and lightweight text formatting. I had converted all of my Wordpress posts to Markdown prior to migrating over to Jekyll and eventually to Hugo. The fact that many generators support Markdown means that my content remains portable regardless of the platform/engine I use.
Scrayos UG (haftungsbeschränkt) uses Java
Shouldn't surprise anyone, as minecraft is also java-based. Java is used for much more than just the plugins though. JCVortex (our API) is also served with vert.x (Java) and many of our team-internal tools also originated from java or are still java-applications.
Web Dreams uses Java
The most popular language in the world, definitely every programmer would use the Java language at some point. Frankly, I only use java when it’s a must. I find the language to be a little bit tedious when working with it.
v0lkan uses Markdown
What you see is not what you get, never it is.
Documentation is better in Markdown format. You don’t need anything special to read it.
It is compact, portable, comparable.
Markdown is my text file format of choice.
brenoinojosa uses Java
bytelore.com makes extensive use of Java in its applications. We use Java due to its performance, community and the number of other projects built in the language. We have many projects and libraries built in Java.
jflynn33 uses Markdown
Because it is almost an effortless markup language without ever having to write an HTML tag. Of course, you'll want to use it in environments that make it look pretty (GitHub, etc.)