Adding to Bitcoin's chip base are those who would like to hold on to bitcoins to conduct regular business, for example, the guy sending bitcoins to China. For me, with all speculative value aside, maybe having $1000 in bitcoins is a convenient amount to have, just so I can pay with BTC to someone who accepts it. This isn't an investment, it's more like cash in my pocket, converted to a form that's convenient. The more people who come along with that mindset, the more demand there will be for Bitcoin.
If a popular legal gambling website starts accepting Bitcoins, that activity will also create a demand for coins, or in other words, it will make a whole bunch of new people suddenly decide that they should hold a few coins for one reason or another, for their utility value. These bitcoins also won't get sold on a whim just to capture a few percent profit. I believe this is the kind of demand that will come in like a tsunami: a huge force that approaches as silently as a whisper.
BTC is more appropriate and efficient than cash in any transaction involving a virtual good. Most people tend to think gambling and porn, but then there is the huge video game market, and there are too many niches in that giant market to keep track of. When niche fans find a quicker way to get that game they've been frothing at the mouth for for months, and be the first to have it and play it, WITHOUT using mom/dad's credit card, well this will help BTC as well.