MeantimeFilter is an interesting new plugin for Rails by Roman Le Negrate. It's a little like around_filter, but rather than using a class with 'before' and 'after' methods, it uses a single method (like the other types of filter) and passes in the method to wrap 'around' as a code block. You can then yield to this or pass it into anything you like. An example:

Paul Battley has developed a Ruby to JavaScript converter. I'm trying to think what this is useful for, but this is an amazing results for just a few hours' work.

Ruby legend whytheluckystuff has developed a new HTML parser called Hpricot. It's easy to install and use and parses HTML in a liberal fashion. It does, however, require a compiler to install (as it's written in C), so should be okay on Linux and Mac OS X, though not necessarily on Windows (yet).

DevX.com has published a great article by Mark Watson entitled "Ruby Programming Language Enables Concise Network Programming". Mark gives quick rationales and examples for:

Flickr.rb is an 'insanely easy' Ruby library to interface with the world's most popular photo-sharing service, Flickr.

TeensyMud is a simple MUD (multi-user dungeon - a bit like a text adventure) server written in Ruby. It's not particularly complex, but it has a great structure and there's a lot to learn from looking at the code (patterns are well used). It's also ripe for extending and for building, perhaps, a proper game or full multi-user environment on.

Mauricio Fernandez's ever-mindblowing Eigenclass presents a great article about how to easily implement a plugin system for any Ruby application. Ruby's reflection and OO features make it a cinch.

The contracts have finally all been signed and I'm (Peter Cooper) already several chapters into writing a new Ruby book, Beginning Ruby, for APress. The information will probably go live on their site sometime in the next few weeks, but you've heard it here first.

Paul Cantrell has created a cool guide, with demonstrations, of the powers, quirks, and surprises of closures, blocks, and procs in Ruby. He writes:

Sending mail from Rails applications using sendmail or a normal SMTP daemon is easy, but GMail has posed some problems. Luckily, someone has worked it out and presents code on how to get ActionMailer sending through a GMail account.