Seek - Thunderbird Email Plug-In for faceted search.

I'm a big fan of Thunderbird as an alternative to Outlook. It's not
perfect, but it works very well on both my Windows laptop and Linux
PC. It also has the advantage of (like Firefox) being open to plug-in
and add ons. That means, if there is a functionality you need, there
is a pretty good chance someone else has needed the same.
I get a lot of emails, and sometimes need to find old emails. The Seek
plug-in adds a level of functionality to Thunderbird that is a hybrid
between filtering and search, they call faceted browsing. I installed it
a few days ago, and have been using it daily. There is an excellent
video and download instructions on this site:
My only complaints - It takes up a lot of screen space. Not a big deal since you can toggle it on and off, but if you do, it re-indexes the folder each time, which is slow. It'd be nice if it indexed in the background, but the interface toggled on and off.

http://simile.mit.edu/seek/

Google Calendar Sync options - Getting better.

Google has finally released support for syncing to your desktop calendar. This could be a very cool tool for keeping multiple calendars on multiple computers synced. Unfortunately, they don't yet support syncing multiple calendars on multiple computers, which for me greatly limits the usefulness of this. But if you're stuck using Outlook, it could be a start, and if they add support for multiple calendars, it could be killer.

The Google Blog post on it.

I have a Google calendar for personal stuff, and several for work. I like to share those with teammates, without them seeing what I'm doing on the weekend. I even keep a few personal ones to keep organized.

It is possible to sync multiple calendars using Thunderbird/Lighting/extensions.
I used this tutorial to set up my Laptop (Windows XP), my desktop (Ubuntu Linux) and they stay sync'd perfectly. Using a different system to sync my smartphone means all three platforms stay perfectly sync'd. I love adding an event on my laptop, and having it appear on my phone.