SlabStay allows you to display items on slabs, the plugin is extremely light-weight and easy to use.
There are currently 2 working commands:
/slabstay add - defines the block you are currently looking at as a "stayslab" or a slab capable of keeping blocks on it. Simply drop the block you want to keep onto the slab and watch it endlessly rotate on the slab.
/slabstay remove - removes the "stayslab" capability from a block you are currently looking at. You can then take any drops off the block/slab.
I am going to support the plugin by all means and there's a ton of features I'm going to add (keeping it light-weight of course). The list of planned features is as follows: