Quaker Texts Online
You may have already heard of Google Books before, but in case you haven't, it is a great resource. Google is digitizing out-of-copyright works from libraries all over the world and making them available. Earlham's Digital Quaker Collection has a remarkable number of Quaker works available as well. Although Google Books offers a search capability, the books typically display as scanned text, so you can't search from within the browser. On the plus side, however, Google Books can typically be downloaded as a PDF, which is a huge advantage over the rather clunky interface of the DQC. Also, some digital archives can be a little funny about the use of their texts even though they are public domain, Google is more open, only asking that you not use them for commercial purposes or do automated queries, and that you retain their watermark.
Some of the works that I have found on Google Books are:
Samuel Bownas' "A Description of the Qualifications Necessary to a Gospel Minister"
George Fox's Journal (If you have a recent Rufus Jones edition, you may find that a lot has been edited out, the ones on Google are more complete)
A Doctrinal Epistle written by Elias Hicks (Purporting to be an exposition of Christian Doctrine respecting the nature and office of Jesus Christ)
Caroline Stephen's "Quaker Strongholds"