Here's a thread from last year with some good discussion, MyHeartBrks:

http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/43004/1.html

Have you checked the Secular Homeschool Forum? This topic comes up often there, as you might expect; here's a sticky with some suggestions:

http://www.secularhomeschool.com/threads/1241-Secular-Science-Recent-Threads

Maybe you could try some Teaching Company courses with a textbook added? Here's their site:

http://www.thegreatcourses.com/tgc/courses/CoursesByCategory.aspx?ps=910

Here's a great blog with lots of secular science ideas:

http://farmschool.wordpress.com/science/

A couple of links for science resources (I'm pretty sure these are all secular, but I haven't seen all of them yet, so my apologies in advance if there's something inappropriate for your needs here):

http://www.middleschoolchemistry.com/
http://www.cavemanchemistry.com/index.html
http://www.bitesizephysics.com/index.html
http://www.biozone.co.nz/modular.php
http://www.singaporemath.com/Secondary_Science_s/31.htm
http://waylifeworks.jbpub.com/samplepages.cfm

Hope you find something you will like using...

peace
minnie