So, here's a companion topic to the one I started on "one pole or two?"
Since we excluded use as a shelter support from that thread, let's start one to discuss using hiking poles (single or paired) as supports for a shelter. The advantage, of course, is that you save the weight of tent poles and get double use from the hiking pole.
In addition to describing your favorite hiking-pole-supported shelter, we can discuss the relative merits of shelters that also need a specific pole in addition to the hiking poles (for example, the TarpTent Rainbow has its own pole set, but also uses hiking poles to optimize the setup.)
My own experience in this area is mostly using a pair of hiking poles to support a tarp. My particular favorite is the Granite Gear White Lightning tarp, a bit heavy but very convenient to use. I've also used the Integral Designs Silshelter with some success. Both were lighter than the tent I had previously used, though that advantage diminished a bit when I added in the weight of the groundcloth or, more often, bivy sack I also carried. I found, with the tarp, that the open ends and sides meant some rain could blow in during a bad storm - not a lot, but just enough that I wanted a light bivy to keep the rain off my sleeping bag. Also, where I hike, biting insects are a problem when it's. A bivy like the Integral Designs Salathe had a waist-length bug panel that was covered by a waterproof-breathable panel for rain, and it worked pretty well. (It also gave me the option of sleeping under the stars on a nice night.) One other advantage of a tarp is that, if you need to, it can be pitched over a small rock or bush in one corner of an otherwise-unusable shelter site - you can't really do that with a tent.
Eventually, both companies came out with floored "bug shelter" inserts - around the same time that the traditional tent companies started coming out with ultralight solo tents. As the weight advantage of the tarp/bivy-or-insert diminished, I eventually made the shift back to a traditional tent because I found it to be more convenient for the way I camp (personal preference, not any objective criteria, drove the switch.)
I briefly used a TarpTent Rainbow, which was a really nice, roomy solo shelter that used an arched tent pole for its main support; trekking poles could be used to turn the vestibule into a roomy porch roof or to make it a free-standing tent. In the end, I sacrificed a bit of weight and a lot of space and chose the Hubba (and eventually Carbon Reflex) because I preferred the all mesh inner with a separate fly that I didn't need to put on unless it was raining. Again, it was mostly a personal-preference choice, and not a case of one product being clearly superior to the other.
Had the tent manufacturers not come out with competitive-weight tents, I'd probably still be using my Silshelter/Salathe combo; at three pounds, it was as versatile as the tent I now use, and did everything I needed it to do. It wasn't as roomy as the Granite Gear rig, but it was roomy enough for a solo shelter and significantly more stormproof since the ends could be closed in. (Granite Gear now offers "Dodgers" which can be used to close the ends of the tarp - but add significantly more weight.)
I really believe that these tarp and shaped-tarp style shelters, supported by trekking poles, are viable options to consider. The Integral Designs combo is a bit pricey; if you're looking for a cheap but effective alternative, combine an inexpensive (relatively) 6x8 or 8x10 silnylon tarp with the REI Minimalist bivy sack. You may even be able to find cheaper alternatives on some of the "cottage industry" sites; I didn't try to do any research there, since other posters will no doubt cover their offerings.