Your OmniWeb bookmarks file is just an HTML file that you can open in any browser and click the links. Look in your ~/Library/Application Support/OmniWeb 5 directory for Bookmarks.html.
I haven't had any problems with OmniWeb crashing under Snow Leopard that I recall. Do you have the bookmark sync turned on? That's reputed to still be a cause of crashes. I'd cc
omniweb@omnigroup.com on one of your crash reports to make sure someone actually takes a look at it, or give them a call.