In addition to purchasing new science fiction titles, I think it's important to ensure that we have some of the classics available. Fortunately the publishing trade loves reprints, so it's possible to fill in gaps and replace worn books from great series such as Isaac Asimov's Foundation. We currently have the seven Asimov Foundation novels for you to re-read or perhaps to enjoy for the first time.
|Foundation||Foundation and Empire||Second Foundation||Foundation's Edge||Foundation and Earth||Prelude to Foundation||Forward the Foundation|
Note that this post shows the order in which the novels were originally published. Some people choose to read Prelude to Foundation and Forward the Foundation as book 1 and 2, since they are prequels to the other 5 stories. Others maintain that the books make more sense artistically if one reads them in the order in which they were published. You choose.
A good series summary can be found in this Wikipedia article.