share mac folder ?

Air Media Server is very good and it works with video as well with a nice built in player. I just have the "generic folder" set to my downloads and then I can watch downloaded videos on my iPhone, and it even converts them on the fly!

However, if you just need to be able to access things like documents, you might want to try signing up for Dropbox and getting the app!

 

I use an app called FileBrowser. It connects to any shared network drives over wifi, and is just like having a file system on your iPad.

 

There are several. I like iFiles. Some support SMB and others support WebDav.