CiviEvent

Tax Calculator

Calculates taxes based on the state or province (instead of a global tax rate, or having to create various forms or line items that use a Financial Type with the appropriate tax rate).

Event ICS

Attaches Calendar ICS files to event confirmation emails.

Advanced Events

This extension provides a number of useful features to complement/improve the CiviEvent component in CiviCRM.

It provides a more useful replacement for the event template functionality.

Google Analytics Event and E-Commerce Tracking

Web Tracking

This feature allows organizations to track traffic for their online event and contribution pages. The tracking reports provide organizations with valuable information like the number of visitors over a specific duration of time, the average amount of time visitors spend on their web page, the number of new visitors vs the number of returning visitors, the type of web browser used by their visitors, the origin/nationality of their customers and a lot more.

Event and E-Commerce Tracking

CiviTournament

Tournaments are a type of event. Participant roles include include players, coaches, parents and volunteers. For academic tournaments, organizations include schools and school districts. Registration includes housing, meals, and competitions. 

multi event map

This extension adds a map displaying multiple events. They can be filtered using the same form as being used in the manage events page. To have this working geocoding should be enabled.

CiviCRM Add to Calendar

Upgrades event iCal buttons to a better looking dropdown that includes a link to Google Calendar.
 
Additionally, this module provides a settings page to configure event description display on Google Calendar.

Event Participant Letter

This extension allows for an email message to be sent automatically, in addition to the confirmation email, upon registration of a participant, using any existing message template. This behavior is configurable for each event, and is useful for sending lengthy or heavily formatted content beyond CiviCRM's standard receipt/confirmation message.