Is this the sort of thing you want?
![Image](http://gimpchat.com/files/6427_flwarpshrink.png)
It was done with Jappaloe63's suggestion of using the Warp Transform tool with Shrink area. I used a round brush size approx. 260, set the Stroke to Periodically and just held the left mouse button down in the centre of the image while it shrunk. Obviously it will look better without the selection dashed lines.