what are the best open source software available?

check this site, all the big open source softwares are available there for free.

http://sourceforge.net/community/

As always the words “better” and “best” depend on who you are. As a sometime artist, I despise Gimp but understand why if you were to list these applications it would be up there. Inkscape is another story — both ways. I use it. I adore it. I see two types of uses it’s put to — and frankly the people trained to be “creative” tend to be less so than the engineers. So if you want to make a list Inkscape should be on it — but you will find more individuals than groups willing to say so.

The other thing which is not exactly an omission given the nature of that list is the GNU tools. Without them, Linux and FreeBSD would not exist. Even proprietary Unixes, including Mac OS X have made some use of them since the 1980′s. And it’s really too basic, too close to the center of the operating system, and frankly too much a package of Developer Tools for them to even mention.

Just my two cents.

I suppose that depends on for what. The page shows several of the most popular CMS and related packages. If that is the only criteria, there may be a few packages missing. If we’re talking in general, that’s another thing altogether.