Problem is that you rarely find good books this way so you have pile of books which are not worth reading. Determining which books are good takes a lot of time. This is reason I have stopped hoarding books from cheap or free sources. It is way better to download/buy/pirate books recommended on the internet than trying to find them myself.
A reasonable strategy for me is:
1. Trawl through a resource like this when I come across them
2. If one looks interesting, do a quick google search of "[sub-category] recommended texts for [my-level] level"
3. Buy or Pirate the top recommended text
Resources like this serve as good inspiration to learn about something new.
