Holding a kayak vertical looks pretty cool and is surprisingly a relatively simple move with a bit of practice. It can lead to move advanced moves such as cartwheels, so it's a good starting point. This article discusses the stern-stall.
The cartwheel seems to be one of the first 'modern' play boat moves that most aspire to perfect. A cartwheel looks pretty impressive but in essence there's not a great deal to it - it's a series of sweep strokes with some careful edging and body rotation - it just takes a bit of practice to bring all the elements together and hey presto, you're there!