there's lots of plugins for flash. if you are talking about some of the trippy 3D effects people do that by using their 3D modeling/ animation apps like 3DSM, lightwave, ect and use a plugin like swish to export the rendered animations into flash. anything that looks impossible in flash is probably exported from another application. most graphics are done with an image editor like photoshop and brought into flash. another flash editor is adobe golive.