If you're using Mountain Lion on the Mac, and iOS 6 on the iPad, and all you need to do is activate iCloud on both devices. This will create an iCloud folder on the Mac. Move any files that you want to share between devices there.
The only caveat is that the files will be converted to iOS or OS X format each time you open them on the corresponding device. This can cause minor formatting problems if you keep moving files back. Not big problems though, at least none that I run into yet.
You can also use the web iCloud interface, icloud.com, to copy files to and from the iCloud account. This only works in a desktop/laptop web browser.
Other than that, probably the easiest method is to mail it to yourself. When the email arrives on the iPad, tap and hold attachment to open in the appropriate iWorks app.