Random 'floating' movement

hi does anybody know how to make an object ‘float’ around the screen? The object will move to random co-ordinates but it will ease into each coordinate… also before it slows down completely it will move off in the direction of the new coordinate - giving a ‘floating’ impression. anyway that is the way i figure it maybe not the way its done… Ive seen this kind of thing around. any ideas. just trying to save time as im not yet a programming whizz!

thanks