Steve points out a new add-on for Thunderbird, Lightning, which adds calendaring capabilities.
If you’re looking for a local client-based calendar, and are using Thunderbird as a local e-mail client, it might be something worth looking at.
You may prefer Lightning if…
- you send or receive meeting invitations via email
- you already use Mozilla Thunderbird for email
- you customize your applications with add-ons (such as extensions or themes)
Mozilla also has a separate calendar client, Sunbird, but I’d think something integrated into a single app would be keen. (“People who like this sort of thing will find this the sort of thing they like,” as Lincoln said)
(For myself, I make use of Google Calendar, and Google Mail, which are also joined at the hip. I have pretty much persistent online capability, between my notebook and my Blackberry, so having something client-based isn’t as important, but if I didn’t, I would certainly consider this.)