Right now, there are 15 blocks you can use.

The first 9 (on top) are solid blocks.

The bottom blocks under 'gravity' are:

-The empty block which does nothing

-The dot makes you float around

-The arrows make you fall in that direction

In Misc. you can find a coin. You can place these and collect them! They have a 3D model to them, so it's pretty nice.

There's also 'blue gravity', which keeps your previous gravity direction. Currently for betatesters+ only. A little video on that: