I came across this site at the end of March, bookmarked it, and then forgot it until seeing it again on Talkbass.
Bass Matter is a labor of love from a bass player named Ryan from Colorado. His “Who is BassMatter” page gives a nice bio and says that he has more than 20 years of experience playing and created the site as a resource for bass players to learn their craft more easily that he did when he was starting out.
There are some nice resources in his Practice Tools section, including charts, jam tracks, exercises and 3 ebooks. Oh, and its all free. Yep. Free. Check it out:
[edit 04.17.14] I just looked over all of the bass charts (in PDF format) and one thing really strikes me – this looks like something out of a White Wolf RPG – the font, layout and general feel. I kind of dig it. 😉
[more edit] The 3 downloadable books are also like this. They’re also packed with a lot of more organic information that I generally see in bass books.