Linux equivalent of Windows Registry
Solution 1:
Linux applications typically store their config in a text-based file specific to the application. Machine specific configs are typically stored in the /etc directory tree. User specific settings are typically in the users' home directory and often in "hidden" files that start with a "." (use 'ls -a' to see them).
Solution 2:
/proc
for kernel related stuff
/etc
for software related stuff
Gnome config can be considered similar to Windows Registry as well.
But since Linux and Windows core philosophies are diametrically different (Linux ~ open and compatible, Windows ~ closed and obstructive), there is no direct parallel.
Edit: for those who disagree, here is a bit of history for you: http://www.faqs.org/docs/artu/ (awesome reading, no matter what your background is)