I really like the smooth water effect you can get with a long exposure, but since it usually requires both a tripod and ND filter I tried this alternative approach with my RX100.
I shot a series of frames with the moving water at normal exposure (1/50s - f3.2 - ISO125 in this case) and used Photo Acute to merge them.
I'm sure Photoshop and other programs can do much the same, but since I have Photo Acute and it's quite decent at lining up the shots that's what I used.
Here's an animated gif showing in the individual frames
And here's the resulting merged image
I'm pretty happy with it as is, but had I used a slower shutter speed and shot more frames the result would have been better.