I actually just ended up dealing with this myself. I had boxes of notes and sketches (I'm an industrial designer) cluttering up my basement for the last 6 years that I just had to do something about. Unlike the original poster's, they were very well organized, for the most part at least.
I was able pare the original six boxes down to less than two using simple criteria such as: (1) is it remotely useful information, (2) is it something that can't easily be found on the internet or in a book I have, (3) is the information easily accessible -- for example, homework sets, labs, and exams usually don't meet this requirement. I kept most of my sketches.
I still didn't want to keep the two boxes, though. In addition to taking up space, they can't be searched and I have to go down to the basement to find anything in them. Scanning is the perfect solution, but unless you have a commercial-quality, high-speed scanner, it's really not worth the time and trouble to do it yourself. So I sent my boxes in to Pixily using their bulk scanning service. They pay for shipping (both ways) and secure shredding if you want. Their rate isn't that cheap, but they did a very nice job and returned high-quality, searchable OCR'd PDFs of everything, properly grouped and labeled based on the file folders I sent in.
In all, it cost a few hundred bucks, which I'm sure many of you are thinking is just plain silly. If so, you should dump your notes in the recycle bin right now (if you still have them). The way I see it, I will refer back to some of this information, and paying to have it scanned actually made the information more accessible, thus it's more likely that I'll actually use it. I could have kept saying that I would do it myself, but the reality is that I wouldn't have taken the time and ultimately I'm glad I didn't waste my time scanning thousands of pages of old notes anyway. My 4-year college education cost a whole lot more than a few hundred dollars, so this was a pretty tiny investment to preserve some of that valuable information.