I didn't do a search so this information has probably already been posted, but
www.ralphpatt.com is a really good sight for practicing jazz standards.
He has put together straight forward jazz standard charts and has backing tracks for almost all of the songs.
The charts are written with "simplified" chords and leave a lot of room for creative improvisation.
I think it is a great site for both beginner and advanced jazz bassists.
The backing tracks easily let you hear changes so that you can internalize them and not have to depend on staring at charts when you are onstage. All the tracks start with a four bar introduction and are long enough to establish the groove and then practice some improvisation.
Like I said, this is probably already on TalkBass, but for beginners out there who need basic charts and backing tracks to play/practice along with it is a wonderful tool.
By the way. I did e-mail Mr. Patt to thank him for the effort he put into the website and how cool it was that he offered it for free. He e-mailed me back to thank me. He thought not many people used the sight and was happy that I found it useful. I though that was cool. I don't know a lot about him, but I think he has played behind many jazz greats and has tons of experience.
The "reformed" Johnny StingRay.