Believe it or not, there are hundreds, even thousands, of free and open source software programs (FOSS for short) available to download on the Internet.
I am a big proponent of FOSS. Many FOSS programs are on par or superior to their commercial equivalent. FOSS is great not just because of the cost, but also because of the quality and frequency of updates.
I have complied a list of FOSS that I use at both work and at home. You can view the list here.