As Chris has recently reminded us, ctext is a terrific resource, both in terms of its textual coverage and the many innovative features that Donald has added to it. Currently it has some very useful coverage of the Song-Ming era, but for anyone looking for more texts from Neo-Confucian authors, I can recommend the Hong Kong Society of Humanities site (click on the 宋明哲學經典 link), which I have just added to our list of resources.