Google gathers all your comments and reviews from services like iGoogle, Google Maps, Google Base, Google 3D Warehouse and lists them at http://www.google.com/reviews/search .
The list of reviews is public, but to get a permalink you need to know your user ID. Here's an example of public reviews page that mostly includes ratings for models from 3D Warehouse. One way to get a permalink for your reviews is to post a comment at Google 3D Warehouse and copy the link displayed next to your comment.
You can visit the discussion threads to read the replies, edit your comments or even delete them. Sorting the reviews by rating could reveal a list of gadgets, places, products or 3D models you found interesting at some point, assuming you took the time to provide feedback.
Google should provide more consolidated interfaces that show data gathered from different services. It would be useful to view and search all your comments from Blogger blogs, get a unified view for all the files uploaded to Google services (Gmail, Picasa Web Albums, Google Docs) or search all the starred items, whether they're bookmarks, Google Reader posts, Gmail messages or documents.