Virto - web part calendar for SharePoint for displaying events in a single view
BSEditor: Color Coded Ajax Webpart Calendar for SharePoint (MOSS 2007/WSS v.3)

Virto Calendar is a new web part for SharePoint that enables users to view all of their events from different SharePoint lists in one single calendar.

Virto Ajax Calendar surpasses the existing SharePoint calendar views functionality by allowing users to specify the list or view, color code the displayed items by category of events such as internal or external, view day, week, month, year, and Gantt view.

Virto Ajax Calendar also provides users with the ability to Create any new event with just a single click! Included with Virto are editing features that will make working with SharePoint easy and pleasant. If you need to change the date of the event, simply drag and drop it to the appropriate calendar cell.
If you need to change the duration of the event, modify the size of the cell to the required direction and length. To change the date, simply select the appropriate date in the mini Calendar. All of these features will help you save time and complete your calendar tasks with the greatest convenience.
Virto Calendar is built on Ajax technology and is designed for Windows SharePoint Services 3.0 and Microsoft .NET Framework 3.5.

Installation is simple and only requires a small amount of time. Currently, Virto supports English, German, Spanich and French languages.
Virto Calendar can be used instead of built-in SharePoint Calendar. It provides you with powerful capabilities for more convenient events calendaring, e.g.:
Google look
Images and Files Preview
Adding Event with a one mouse click
Event Coloring according to List Type
Date Picker for quick and easy navigation
Event duration editing with a simple resizing action
Event date changing with a just drag and drop
Single aggregated view of all your events from different SharePoint Lists not only single SharePoint Site
Resizing for fitting your web page design
Printing of any Virto SharePoint Calendar View you can free download Virto Ajax SharePoint Web Part 2.2.4 now.