Starry Night -
It allows you to view the sky from any location on Earth on any date from the past of future, including special events
(eclipses, transits, etc.). It's a great aid in planning astrophotography (or observing) sessions.
You can see when things rise and set, which direction and where in the sky they'll be visible,
and you can even zoom in to get an idea of how things will look when magnified through your telescope.
If you want a Starry Night like planetarium sofware for free, then Stellarium is a great option. It will suffice to show you when and
where the moon, stars, planets, and more will appear from any location on Earth. Give it a try, you could find
that it's all you ever needed when it comes to planing your astronomy or astrophotography adventures! And the price couldn't be more convenient!
Photoshop - This is practically one of the best image editing software available and
can be used to enhance your pictures. You may not need such an advanced program, but at some point you'll probably
want to see how you can enhance your pictures digitally. Some basic information about digital processing that will help you make use
of such a program as well as others is covered in the books and articles listed above. I've definitely been able to improve the quality of my pictures by digital enhancement. More astrophotgraphy-specialized programs are available
for specific tasks (such as stacking, making star trail pictures, etc. - see below), and can be more efficient and easier to use than Photoshop for those
Registax - This program is very useful for processing webcam images.
It allows you to select the best frames from video webcam recordings, combine these frames, and process them to bring out the details.
Registax can also be useful for digital processing of non-webcam images. This program is free.
DeepSkyStacker - Is useful for processing deep-sky images.
You can combine several images, subtract dark frames, and other processing and post-processing tasks. This program is free.
Startrails - Makes combining consecutive exposures to make startrails
extremely easy. This program is free.
Starstax - Allows you to make startrails in addition to a "cumulative saving" option, which
is helpful for making individual frames for a star trails movie.
Neat Image - A useful free program for noise reduction