The vast majority of my work involves maintaining a system written in MUMPS, running on InterSystems Caché.
This may be the Stockholm syndrome speaking, but it's pretty alright. And I say this working with extensively with, among other things, Python and JavaScript also. My educational background is an MSc in Physics, so I'm also familiar with everything from MATLAB to LabVIEW to Assembler to PHP.
Ask me anything!
$ZCONVERT(stringVar, "O", "JS")
Which escapes stringVar into a valid JavaScript string without quotation marks doesn't escape line separator or paragraph separator (U+2028 and U+2029), when it should.
This was also a bit of a problem in browsers, JSONP and the JSON spec a while ago. Life in the MUMPS world isn't as bad as you'd think. Except for a lack of nice libraries. You do not want to know when regexes made it into the language. Last year. But there has been something similar - pattern matching - which alleviated the need for them a bit. And calling out to DLLs is fairly easy. It's really driven more by the healthcare industry than anything else.
Also, here's a short FizzBuzz I wrote:
Written in pseudocode: Shorter than any other FizzBuzz I've seen other than Perl, yet probably more readable.