The link above is a good source of piano playing knowledge because once you know a scale and get the feeling of it you will be able to improvise on that scale. It also makes learning songs by ear easier as most songs stick to a specific scale.
Some piano playing terms are: Counterpoint, Alberti Bass, Trills, Staccato and Dynamics
Counterpoint is the relationship between voices that are interdependent harmonically yet independent in rhythm and contour. One simple way to create counterpoint is to repeat a melody that you played on your right hand on your left hand. Or another way is to make your left hand accompany the melody in an expression very similar to the original melody and maybe played just a few beats behind with unexpected melodic 'twists'.
Alberti bass is a kind of accompaniment where the notes of the chord are presented in the order: lowest, highest, middle, highest. This pattern is then repeated several times throughout the music. This pattern helps to create a smooth, sustained, flowing sound on the piano. You just might want to give it some variety to keep things interesting.
The trill is a musical ornament consisting of a rapid alternation between two adjacent notes, usually a half-tone or whole-tone apart.
Staccato signifies a note of shortened duration,
separated from the note that may follow by silence.
Dynamics of a piece are the variation in loudness between notes or phrases.
Thinking outside the box, EFFECTS
"Ring Mod" is a great effect to use for heavy distortion.
"Chorus" effect is good to detune the voice.
There is also a "Sepia" effect that may be added to make the voice 'sound older'
Thinking outside the box, UPSIDE-DOWN
Playing a keyboard upside-down is also a good way to reinvent your creative style.
The comedic pianist, Victor Borge, had a bit where he would play a strange-sounding piano tune, looking increasingly confused. The sheet music was upside down! Then he would turn it right side up and say, "ah that's better!" It was done as a joke, but I think upside-down or side-ways sheet music could be a great inspiration for some unique ideas!
Thinking outside the box, THE BLACK KEYS
Improvising only on the black keys makes you an instant master.
Almost anything you play just on these keys will sound good.