The one I am using I converted from a 2k Earth map, but the oceans are simply too dark. Here is the standard texture that I use for oceans:

Minus the small land areas, of course. I suppose it could simply be an artifact of my video card, an Nvidia TNT2 32mb, which I think is not working properly with my system.
Still, if anyone has a better "blank" map like this, I'd love to know, and possibly use with permission. I've tried lightening the above texture via photoshop and PSP, but everything I try simply makes it look worse in one way or another.
Thanks...
...John, working on 36+ hours with no sleep...