The hackers behind RubyCorner have put together a nice little Google Custom Search tool. It sits unobtrusively up in the upper left corner of the main section of their page, waiting for you to try it out. Not only have they put together a good list of major Ruby and rails resources, every blog registered there is part of the search domain.
The Ruby aggregator field is getting a bit crowded, and I really haven't decided which of the various aggregators I like best, but RubyCorner is leading the pack from my perspective. I like the look they're developed, and they've put some effort into a number of nice little features (like filters based on language, favorites and blacklists, and a bit of user preference tweakability).
One thing I'd really like to see them add, is a remem style cross index. I've brought it up to Anibal and Edgar, but it's a big project, and it's not like I'm contributing code to make it happen. In the meantime, I'll just keep wishing.