Blinking text, marquees, or animation may easily be overdone. Motion on a page draws the eye to it. This may be useful if the lively item helps to convey information or serves a purpose. Motion used strictly for entertainment may be fine, but a trick that amuses at first can quickly become a distraction or an annoyance. Keep in mind that if a page needs disclaimers about its functionality, it is probably not ready for public viewing.
Users expect, even demand, that pages continually grow and evolve.