I use a MacBook (C2D, 2.16 GHz, 160 GB HDD) which multiboots OS X and four Linux OSes.
I can easily access/read/write OS X files from all of the Linux partitions but the opposite transaction is less straightforward.
I came across Ext2fsx and installed it in OS X.
However, it seems just a little temperamental. For example, of the eight (/ and /home for each of the four OSes) ext3 partitions I have on my MacBook (Ext2fsx is claimed to cater for ext2 AND ext3 partitions) only two actually are mountable. I have made many different attempts to mount the remaining six, even after unmounting the two mountable partitions, but all to no avail. I can, however, read almost all of the files on the mountable partitions although writing is not possible.
Additionally, I have an external usb HDD which has twelve ext3 partitions. When I plug this into the Mac, only eight of the twelve ext3 partitions automount.
Although ext2fsx seems to me to be a potentially extremely useful little utility, there is really very little general information available on the web.
I would very much like to hear from anybody who has some practical experience with ext2fsx, good or bad, and who can perhaps help me make some progress in understanding how to get more out of it.

Four Linux OS's on a MacBook? How cool is that!

Like you [hushed voice] I'm a Mac fan and have also used Ext2fsx to try to access my ext2/3 drives.

I'm afraid that my experience is exactly the same as yours - some work and some don't without a great deal of logic as to why.

My only tip is that I have found the Ext2fsx GUI unreliable and that mounting the drives via a terminal works with a much better level of success.

Despite reading a number of posts that claim various OSX and Linux tweaks that allow write to ext2/3 drives I have never managed it.

Hi Unknown_User
Thanks for sharing your experience with ext2fsx. So, from this and a host of other posts I've seen, it really seems that ext2fsx is not quite ready for the big time.
Nevertheless, I'm intrigued by what you say here under.
I have not had any success with attempts at CLI mounting of ext2/3 partitions in OS X. However, I can use the GUI to umount/mount the only two (internal HDD)partitions (ext3) that tend to automount on booting into OS X.
I had tried a CLI mount of one of the ext3 partitions that NEVER automount using
but I get this
Perhaps you could let me know what mount command was successful for you.