$LiveCalendarWidget isn't doing that for you? Should be.

There's a hack for that.. I haven't put it in the core because it adds a lot of database overhead to your page, but here you go:

On line 206 in CalendarUI.class.php, there's an array that accepts all the data for a given day in the calendar. You'll see that "HasEvent" is one field. After that entry in the array, add:

'Events'          => $this->calendar->Events(null, $this->date_counter->date(), $this->date_counter->date()),

And on LiveCalendarWidget.ss:

<td class="$Today $OutOfMonth $CurrentDay $HasEvent">
<a href="$ShowDayLink">$Number</a>
<% if Events %><% control Events %><a href="$Event.Link">$Event.Title</a><% end_control %><% end_if %>
</td>

I ended up using this to display icons for each event on any given day with events. On rollover more details appear via a little javascript. I had to do another hack to CalendarUI.class.php to make the page reload (so the hidden divs would load) when using the next and previous month buttons in the widget:

'PrevMonthLink' => $this->calendar->Link('view')."/".$this->start_date->subtractMonth()->format('Y-m'),
'NextMonthLink' => $this->calendar->Link('view')."/".$this->start_date->addMonth(2)->format('Y-m'),

Just in case anyone wanted to do something like the attached.

I'm doing a similar thing with the event_calendar as smallstudio did and I changed the CalendarUi.class.php as followed

'PrevMonthLink' => $this->calendar->Link('view')."/".$this->start_date->subtractMonth()->format('Y-m'),
'NextMonthLink' => $this->calendar->Link('view')."/".$this->start_date->addMonth(2)->format('Y-m'),

If i now use the link the following Message will show up:

Fatal error: Call to a member function get() on a non-object in [...]/event_calendar/code/CalendarUI.class.php on line 204

if i open the link in a new window, everything works fine.
Does anybody has a clue, whats going on here?

Thanks for help