For "synchronicity" (a la Textures) you need to follow the instructions in the readme that comes with TexShop, throwing pdfsync.sty into ~/Library/texmf/tex/latex, for example. After that it's just a matter of using

\usepackage{pdfsync}

in your source file and you can command-click in either source or output to "synch" the two files. That is, jump from a given spot in the source/output to the corresponding place in the output/source respectively. It's working really well now.

For more TexShop fun don't forget to use the "esc" key when entering tex commands: it'll try to complete what you're typing, using the entries that you can see (and modify) via the Format->Completion->Open Completion File... menu item. It works beautifully (as does the macro facility). All in all, quite beautiful!