Pretty much anything. Cuttings are divided into two categories, softwood cuttings (flowers, vegetables, other obvious "soft" plants) and hardwood cuttings (trees, woody shrubs, etc.). Softwood cuttings are much easier to start... just get some root tone powder, dip the end of the cutting in it (where you want to grow roots) and place it in well-watered soil (though over watered cuttings will begin to rot).

For hardwood cuttings, you may do the same, but place a plastic bag over the pot and the cutting to maintain a high humidity level around the cutting. Again, do not over water or it will rot.

Don't place cuttings in direct sun, and DO NOT pull at them to check for roots. I know its tempting but it will destroy the project.

Have fun!

Plants with thick, succulent leaves tend to be easier to propagate with leaf cuttings. African violets are easy, as are kalanchoe, stonecrops, Aloes, Echeveria, Sanseveria, Jade plant, etc.

It is easy to experiment since taking a leaf off of a plant does not change its appearance much. Succulent leaves can be rooted without a cover, and it may even help to allow the cut end to dry out for a few hours or a day for plants like Aloe. A loose rooting mix with lots of perlite can help prevent fungal infections and encourage root growth. For other plants it may be necessary to use a rooting hormone and maintain high humidity around the cutting.

I just noticed that this was in the ROSE propagation forum as I sent that reply. I thought this was the regular propagation forum. Wish they could let us edit our posts here.