Okay, I tend to shop in the bulk section for basics like rice, beans, etc, and I always make a mess when I either pour my stuff into a new container or try to scoop it out. Yeah, I'm kind of accident prone/messy when I'm in the kitchen...
I got this idea from a plastic bottle lid recycling project found here: http://www.re-nest.com/re-nest/hot-tip/a-useful-reuse-for-plastic-bottle-caps-128400 , and I thought it was brilliant! However, I had a ton of vitamin bottles with flip-top lids (and pretty colors) that I thought might work better--you are at less risk of damaging the plastic bag because you are only tightening the lid with the threads once and just reusing the flip-top to pour out your goodies.
Because the vitamin bottles are thicker plastic than a water bottle, you need to use a saw (I used a 99 Cent Store hacksaw) or utility knife (please be careful!) instead of scissors.
I find that my goodies take up less space this way, I can see how much I have left, and I don't make as much of a mess when I'm trying to get to my stuff...
Using the sticker already on the vitamin bottle as a guide to keep your cut straight, cut the top portion of the bottle and lid off. PLEASE use proper technique for safety! I am only using bad technique because I'm holding a camera!
Remove the lid and pull the plastic bag with your goodies in it through the neck of the bottle. Fold the plastic bag out like a flower around the opening.
Replace lid by tightening it around the plastic bag. Trim the bag, if necessary. You now have an easy pour spout and a tight seal on your plastic bag! Use for candy, cereal, dry goods, etc.