@pq: Depending on the version you're after, the following applies:
The "tcz" directory is the location of "packages" (or extensions as it's called here.)
The "x.x" directory is a version number such as 4.x, 5.x or 6.x
The "x86" directory is platform specific; if using 64 bit, the platform directory would be x86_64 and more recently corepure64
http://www.tinycorelinux.net/6.x/x86/tcz would show you a list of extensions for version 6.x on x86 platform.
ARM, x86, x64 (pure) and x86_64 (64b kernel, 32b extensions) along with a ton of other content can be found.
Suggestion: First, read the wiki (Tiny Core Linux Concepts - link at the top of this page) to get a feel of what's what. Once you have the concept of how the pieces fit together, then choose a version you want to "browse" and append that to the tinycorelinux.net site name as shown above and go from there. When downloading (instead of just browsing) please hit a mirror with the same conceptual directory structure.
The "best" way if you're new to TC (in my opinion) is to nab a copy of TinyCore or CorePlus, burn the CD and boot it. Then just use the Apps program to browse with as it gives a lot more detail as opposed to just browsing thousands of file names on the web. If you've already done this but want a CLI method to pull in files, the program
tce-ab is a command-line version of Apps allowing a basic search feature. If you already know the package's name and simply want to install it by command line,
tce-load -wi package.tcz does the trick. If that's still not enough (such as if you're writing a program and need a more "direct" approach) the following applies:
wget http://www.tinycorelinux.net/4.x/x86/tcz/filename.tcz
wget http://www.tinycorelinux.net/4.x/x86/tcz/filename.tcz.dep
wget http://www.tinycorelinux.net/4.x/x86/tcz/filename.tcz.info
wget http://www.tinycorelinux.net/4.x/x86/tcz/filename.tcz.tree
* Again, please use a mirror near you for this
Hope this helps!