You want your frameless shower doors to look free-standing and transparent with the least amount of hardware possible. There are, however, a few essential hardware pieces.
In order to hold the glass in place, you need metal clips that you install into the tile. The glass fits between the clips. These clips are small, about 3 inches square and will come in a finish to match your other hardware. They blend into the shower and won't seem intrusive.
Frameless shower doors that swing will need hinges. These hinges can connect directly from the wall to the door, depending on the design. When they connect from the wall, they don't block the view of the shower or take away from the clear look.
If your shower door is movable, you'll need a handle to operate it. The style of the handle will depend on your personal preference, but it's not hard to make it blend in with the rest of the look.
The most important feature of frameless shower doors is the lack of metal rails around each piece. If you can avoid those, the minimal hardware won't bother you.