As much as photographers love to brag to one another about how steady our hands are, the simple truth is that the best way to extract the most amount of image quality from our cameras is to mount them on tripods. However, carrying a tripod can be prohibitive, both in terms of personally practicality and in terms of permission of use (think museums). Joby has been selling the GorillaPod line for years. Though it is not longer the highest end of then range, the SLR-Zoom model is rated up to 3kg and sits in the butter zone as far as price to performance ration goes. It's bigger brother, the Focus, can hold 5kg and was meant for heaviest bodies like the D3. The following image is a D7000 with a Tokina 50-135, which would tip the scales at just over 1.5kg. It sits comfortably on the SLR-Zoom when mounted with the tripod collar. However, if you try to mount the pod on the body, the lens will not be able to stay up and will droop slowly but surely, so I really wouldn't push the 3kg hard unless there was no other choice.
There are a few no-name knock-off's out there. I see them every year at our summer night market and they are usually very cheap and of limited usability. I have yet to see one where the legs are as sturdy as the real GorillaPod, and while I might use a no-name for a lighter camera, almost none of clones that I have played with are sturdy enough to hold mid-range dSLR gear... except for maybe in a perfectly upright position with not too much weight to cantilever the device out of position.
Portability is a big plus with GorillaPod's. Here you have it tucked away in the Crumpler 5 Million Dollar Home, which is a modest-sized three-lens messenger bag.
When you are not busy hanging your dSLR off of awkward perches, GorillaPod's are also great for shooting macro's with smaller cameras.
So long as you can wrap the legs completely around a support surface, the pod will stay anchored on most railings. The rubberized leg rings help with the grip, buy the key is that the articulations stay in place once you have bent the legs into the desired shape. That's my camera you see in the following picture, and yes, that's the mouth of the Fraser River below.
In situations like this, the GorillaPod has an advantage over proper tripods: some railings are too high to shoot over and frame properly with a tripod. For less tripods, you will also have to extend them all the way until rigidity is not optimum. Mounting right on top of the railing gives you a good view and good stability. Here is an example of what you can achieve with a good setup: from the red railing above, if you turn to the right you will see this twilight scene during the late summer months:
A word of warning though. You absolutely must shoot in mirror-up or mirror-delay mode. You can also use Live View if it's a newer camera, but beware, some older cameras (like the D3x of all cameras) drop the mirror back down when you take a Live View shop in order to take an exposure reading. Because the legs of the GorillaPod are short, that means that they are also a mechanically stiff system that transmits shock easily. And by shock I mean vibration from mirror slap, as evidenced in this picture:
Because the above was a long exposure, most of the low-luminence detail came out very crisply, but if you look at the city lights in the foreground of the high-rises you can see the effect that the vibration had. In a long exposure shot, the lights will "burn in" the quickest, meaning that they're exposure was set during the time when camera vibration has highest. If you take GorillaPod pictures with a D7000 strapped tightly to a railing, at some shutter speeds the mirror slap is so strong it looks like you took a shaky-hands picture without a tripod.
And lastly, one final warning:
I take absolutely no responsibly if your camera falls into the drink using one of these things. Or if you do something silly like try to strap your camera upside-down from the rafters. Note that in each instance my camera is attached to the railing with the neck strap is deliberately placed so that it can be grab just in case of the unthinkable. "Just in case" has never happened and I intend to keep it that way, but the GorillaPod hasn't given me reason to worry either.