Tcl and Tk are excellent scripting and visual toolkits that don't get enough attention. Here's the description from the main website:

Tcl (Tool Command Language) is a very powerful but easy to learn dynamic programming language, suitable for a very wide range of uses, including web and desktop applications, networking, administration, testing and many more. Open source and business-friendly, Tcl is a mature yet evolving language that is truly cross platform, easily deployed and highly extensible.

Tk is a graphical user interface toolkit that takes developing desktop applications to a higher level than conventional approaches. Tk is the standard GUI not only for Tcl, but for many other dynamic languages, and can produce rich, native applications that run unchanged across Windows, Mac OS X, Linux and more.

Tk is the GUI builder on top of Tcl, and is more well known. Tkinter is a Python interface on top of Tcl/Tk, and is probably more popular than plain Tk because of the large base of Python users.

Tcl as a scripting language doesn't get enough attention, in my opinion. Because it has such good networking capabilities, Cisco has adapted a version for programming their routers.

Here's an interesting read from the Tcler's wiki on functional programming in Tcl. An small excerpt: I'd say that Tcl is often used imperatively, but at bare-bones it's fully functional - just by the fact that every command returns a result - take it or leave it...

Tcl is very simple, to the point of being sometimes hard to understand at first. Most other languages have built in statements for "if... then... else", but in Tcl these are actually separate commands. There are no types, but rather everything is a string. These strings are used in context, so if a procedure is expecting an integer and is passed a string with text, it will complain.

Tcl was designed to be extensible, and there are many extensions. One is Expect, which can mimic a human interacting with a program. Here's one of my stories:

I was working with Brian Kernghan on a Tcl/Tk laptop client that needed to interact with a server using the AMPL language to run math solvers. AMPL at the time had no API, and needed to have a human typing commands into a terminal. Using Expect I was able to connect the client to the server, automate input and get the results. I don't know how else I could have done it.

Another useful extension is TclX, which adds Unix/Linux system programming commands. Normally system calls to interact with the kernel are done in C, but this extension allows them to be scripted. TclX turns Tcl into a real systems programming language capable of process forks and execs, shared memory, semaphores, etc.

Even plain Tcl is capable of bit-level manipulation. Here's another story:

I was working with AT&T's Conversant programmable telephone switch at Bell Labs, and wanted to extract some audio to playback using a PC sound card. Conversant uses its own proprietary audio file format, and on examination I saw that it looked like a standard 16 bit μ-law format, but with the the high and low bytes flipped and an extra header. I wrote a Conversant-to-μ-law converter in about five lines of Tcl, using the Tcl 'binary' command. The conversion itself was one line of code.

I believe Tcl is far superior to Perl, and in line with Python. Python's strength is in its huge number of libraries and resources, but as a language, I like Tcl better. I've used both quite a bit, and this is our preference for scripting. If it's best for your applications, I'd' be happy to discuss it with you.