So VNB and I have a pretty small place (~1000 sq. ft.). This smallness is compounded by the fact that when we married and moved in together, he was coming from an apartment of about 900 sq. ft., and I had stuff that had filled most of a 3-br house prior to storage in my brother's basement (while I was overseas).
Since I didn't have a job right away when we got married, I spent my days culling through my stuff (for a second time - I'd done it once before it went on the truck to come here from my brother's house), getting rid of lots of stuff, and finding lots of creative places and ways to store things.
Well, we'd found a place for everything (finally), with half of the space under the bed to spare when we visited VNB's folks and were given seven boxes of his childhood stuff - way more than half the bed. So he culled through that and we'd finally found a place for everything (which included "just put it in the second bedroom for now")...when we found out that I was pregnant and we were going to need that second bedroom for baby things, rather than our things.
So we both culled through everything again and got rid of another large chunk of stuff until we had room for all the baby furniture and stuff we could stand. Everything sort of had a place, but it was overwhelming. We put lifts under the bed and the futon to give us more space, but the whole place was still just too full. The problem was that we'd gotten to the point where if we threw stuff out, we'd want to buy it again when we got a bigger place.
We'd seen the SpaceBags commercials time and again, but one night, VNB said, "why don't we try those?" So we bought our first box (the one with lots of different sized bags). We were hooked. We started SpaceBagging everything that would shrink, and all of the sudden, we had room to spare again! So we bought more and bagged more stuff! and more! Until the only stuff left wasn't smushable!
They haven't been great about keeping their integrity (we've got a few that are still good, but not all of them), but the good thing is that you can suck them down, stick several of them into someplace small, then they can re-expand all they want without taking up any more space for you! They're a little harder to get out, but that's not a big deal.
In any case, SpaceBags have definitely worked for me! For some other great tips, look here.