Convert Generic List to String

var stringBuilder = new StringBuilder();
 strings.ForEach(a=>stringBuilder.AppendFormat("{0}:",a));

Sharepoint Calender

Add Holiday Calendar to SharePoint:

http://www.sharepointdev.net/sharepoint--general-question-answers-discussion/add-holiday-calendar-to-sharepoint-1284.shtml

Understanding the SharePoint calendar and how to export it to iCal format:
http://sharepoint.microsoft.com/blog/Pages/BlogPost.aspx?PageType=4&ListId={72C1C85B-1D2D-4A4A-90DE-CA74A7808184}&pID=761

// Get the Events list

SPSite site = new SPSite("http://localhost");

SPWeb web = site.RootWeb;

SPList calendarList = web.Lists["Calendar"];

// Construct a query that expands recurring events

SPQuery query = new SPQuery();

query.ExpandRecurrence = true;

query.Query = "";

// Look forward from the beginning of the current month

query.CalendarDate = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);

// Returns all items (including recurrence instances) that

// would appear in the calendar view for the current month

SPListItemCollection calendarItems = calendarList.GetItems(query);

foreach (SPListItem item in calendarItems)

{

Console.WriteLine(item["Title"] + ": starts "

+ item["EventDate"].ToString() + " and ends "

+ item["EndDate"].ToString());

}