Solar and wind are the most common technologies for small-scale off-grid electricity generation, but micro-hydro turbines are growing in popularity, due to a variety of advantages they have over other technologies.
Although there is some initial setup cost, this is not much different than similar-capacity solar or wind systems. Micro-hydro generators don't require a reservoir and can be designed as a ‘run of river' system. Unlike wind and solar, micro-hydro energy sources are not subject to the same rapid, unpredictable fluctuations, although seasonal variations are a factor. With careful design the environmental impact will be negligible and although hydro is not free power, it can be very cost-effective over the long run.
Here's an example of a medium-sized micro-hydro system in use at a remote lodge. It has the potential to generate up to 12 Kw of electricity, approximately ten times the consumption rate of an average U.S. household.
As with any project focused on self-sufficiency, micro-hydro is usually only a partial solution. Ideally, some form of storage system and perhaps supplementary wind and solar generation offer the best reliability. Environmental laws vary from region to region, but will likely require some type of permit to install a micro-hydro system. In some cases government supports self-sufficiency, but in many situations, government and the power industry actively resists this type of individual effort, so be expect a certain amount of red tape if you want to implement micro-hydro into your off-grid plans.