One of my favourites is a great (and free) piece of software called GraphicsGale. This is PERFECT for those who want to dabble in pixel art or animations.
If you want to have a go yourself, I would say a great way to start is by using Pokemon as your models. Even if you are not fan of Pokemon or consider yourself "too old", they are cute and unusual creatures so they are fun to draw. This is exactly what I chose to do and it got me hooked!
It is very simple to use which makes easy for novices and it's a lot of fun to use. If you're like me though and aim for perfection, you could find yourself getting a little frustrated if you miscount the pixels or can't get the shape of something quite right.
This is definitely worth a try if you're considering getting into digital art or you just want something different to do today.
Here is the link: http://www.humanbalance.net/gale/us/
Create. Have fun. Share!