Scholarpedia
Scientific knowledge should be widely and freely available. Of course it is nice that scientist can earn an extra buck by coauthoring a book and I’m not advocating that they should not be (financially) rewarded for their efforts, but making the work only available in a usually quite expensive, offline form prevents most works from reaching a sizeable audience and thus attain general usefulness that would be deserving of the quality of the content. Also, a lot of (introductory) knowledge is repeated over and over again in these books and while it can be useful to learn about a subject by yet another approach, most often there exist better treatments of the material elsewhere. Either the reader is already familiar enough with the material to even recognise casual errors in these sections or he would certainly be better off reading another text, that focusses on that particular subject.
This is why I am hoping that projects such as Scholarpedia, MIT’s OpenCourseWare and many other initiatives to make scientific knowledge and teaching material generally available, will gain traction in the coming years. Wikipedia is of course another fine example of a great body of knowledge, but their particular approach of building scientific knowledge does seem to have some problems. I would not want them to stop their efforts, but parallel initiatives, that explore other ways of making scientific knowledge widely available, mostly trying to solve the problem of accountability and credibility, are to be followed closely and be given a deserving piece of the total attention.