Below is software that I have found useful in my Ham radio endeavors.
Ubuntu Linux
Ubuntu, like most other flavors of Linux, is a free, stable and highly reliable computer operating system. Linux is well known to be far more stable than Microsoft Windows and Ubuntu is no exception. Ubuntu is the most user friendly Linux distribution that I have used and has quickly become my OS of choice. All software that falls under the Ubuntu umbrella is free software. There are thousands of free programs available that are Ubuntu compatible and can be downloaded and installed using tools included with Ubuntu. If you've shied away from Linux because you felt like your computing skills weren't up to snuff, perhaps you should give Ubuntu a try. Its the easiest, most user friendly distribution of Linux available.
DXKeeper
I have been using DXKeeper for a couple of years now and have found it to be very good. The thing I like best is its ability to automatically upload logs to eQSL and LoTW. This is a wonderful feature. The price is also right at $0.00. Free is always good.
DigiPan
I chose DigiPan over several other free PSK31 programs primarily for its multi-channel capability. DigiPan will decode many waterfalls simultaneously. At a glance you can see if anyone is calling CQ or calling your station without having to click on each waterfall. You can also configure DigiPan to change the color of a channel when a predefined string of text is found. For example, I've configured DigiPan to turn a channel red when it sees my call sign and green when the letters CQ appear. DigiPan is free.
Orbitron
Orbitron is satellite tracking software. Orbitron shows real time satellite positions and will also calculate future passes. It not only shows OSCAR satellites, but practically every other satellite in orbit. It also provides rotor control for keeping your antennas pointing at the bird as it passes overhead. Like my other software Orbitron is free.
Satellite Tracker Plus (iPhone)
Satellite Tracker Plus has much of the same functionality as Orbitron. The real advantage here is that it fits in your pocket and it's with you whenever you have your iPhone. If you have an iPhone and work the satellites, this is a must have app.