Drag and drop your way to Android programming. MIT App Inventor, re-released as a beta service (as of March 5, 2012) by the MIT Center for Mobile Learning after taking over the project from Google, is a visual programming language for developing applications for the Android mobile computing platform.

As with many of the challenges we tackle, the latest project has sprawled across more articles than I ever expected when I first received the query from a reader. The question seems reasonably simple: given a month, day number and day of the week, calculate the most recent year that matches those criteria.

You've built the hardware, installed the software and cracked some passwords. Now find out how to fine-tune your attacks.

A high-availability stack serves one purpose: through a redundant setup of two or more nodes, ensure service availability and recover services automatically in case of a problem. Florian Haas explores Pacemaker, the state-of-the-art high-availability stack on Linux.

Playing and managing your music in text mode.

Internet Relay Chat (IRC) is one of the older real-time communications methods still in active use on the Internet. Due to its popularity, flexibility and cross-platform nature, it still has a very vibrant user base today.

For those of you playing along at home, you'll recall that our intrepid hero is working on a shell script that can tell you the most recent year that a specific date occurred on a specified day of the week—for example, the most recent year when Christmas occurred on a Thursday.

Your hardware is ready. Now, let's load up some software and get cracking.

Directory services is one of the most interesting and crucial parts of computing today. They provide our account management, basic authentication, address books and a back-end repository for the configuration of many other important applications.

In this article, I'm diving into chemistry again. Many packages, both commercial and open source, are available to make chemistry calculations at the quantum level. The one I cover here is gromacs (https://www.gromacs.org). It should be available for your distribution via its package manager.

Bitcoin mining is so last year. Put your expensive GPU to use cracking passwords. When the Bitcoin mining craze hit its peak, I felt the tug to join this new community and make some easy money. I wasn't drawn only by the money; the concepts behind Bitcoin mining intrigued me, in particular the new use of graphics processors (GPUs). With a moderately expensive video card, you could bring in enough money to pay off your initial investment and your electricity bill in a relatively short time.

Catalyst is the latest in the evolution of open-source Web development frameworks. Written in modern Perl and inspired by many of the projects that came before it, including Ruby on Rails, Catalyst is elegant, powerful and refined. It's a great choice for creating any Web-based application from the simple to the very complex.

HTML5 lets you play music through compliant browsers—no "cloud" required.

Don't be afraid of using your chosen database's command-line client.

If you've ever worked with pranksters, you've probably come across this classic office prank. First, the unsuspecting victim leaves his computer and goes to lunch or a long meeting and doesn't lock his screen. The prankster then takes a screenshot of his current desktop, hides all the desktop icons and any taskbars, and sets the background to be the screenshot the prankster just took.

For the past several years, I've used a custom-built file server at my house. I've upgraded it many times, but it began life, as near as I can recall, in April 2000. When I say "upgraded", I mean the internals have been swapped completely on at least two occasions among other things.

"If we see light at the end of the tunnel, it is the light of the oncoming train" ~ Robert Lowell. Oh yes, another good quote. This post is on SSH tunneling, or as I like to call it 'Poor Man's VPN'. Contrary to the sysadmin's popular belief, SSH tunneling actually can be very valuable use for both techies and home users.

Portable music doesn't need to be restricted to headphones. Here's a step-by-step how-to on setting up a music system that follows you around the house like a puppy.

This article should acquaint you with basic Arduino programming and show you how to write programs that interact with objects in the real world. (A mandatory disclaimer: the last time I really studied electronics was way back in high school, so this article focuses more on the programming aspects, rather than the electronic side of things.)

In a previous article, we started a script that worked backward from a day and month date and figured out the most recent year—including possibly the current year—that would match that date occurring on that particular day.