Yes, with some caveats:
With the above caveats, this should be at worst fair use, but I am an engineer, not a lawyer. (I am, however, finishing up a class on US intellectual property law, which clarified much of my understanding of the law in this regard.)
I'll limit myself to 2 requests for entire books (first come, first served), as the scanner they have is not ideal for scanning entire books. They have a good overhead scanner, but it's somewhat slow.
It's a Mexican book that used to be available in libraries here in Colombia around 6 years ago. Today it's nowhere to be found, and all my known pirated sources for books in Spanish lack it. It's not available for Kindle, and the LoC happens to have it.
However, I just checked in Amazon that the printed version has 401 pages, which makes me feel embarrassed to ask for such a cumbersome favor. Upon further search, I discovered one public library in my city that has it available for loan. I'll do that.
Over the last year, VincentYu, gwern and others have provided many papers for the LessWrong community (87% success rate in 2012) through previous help desk threads. We originally intended to provide editing, research and general troubleshooting help, but article downloads are by far the most requested service.
If you're doing a LessWrong relevant project we want to help you. If you need help accessing a journal article or academic book chapter, we can get it for you. If you need some research or writing help, we can help there too.
Turnaround times for articles published in the last 20 years or so is usually less than a day. Older articles often take a couple days.
Please make new article requests in the comment section of this thread.
If you would like to help out with finding papers, please monitor this thread for requests. If you want to monitor via RSS like I do, many RSS readers will give you the comment feed if you give it the URL for this thread (or use this link directly).
If you have some special skills you want to volunteer, mention them in the comment section.