task
Essentially, count the number of occurrences of =={{header| on each task page.

Output:

100 doors: 20 examples.
99 Bottles of Beer: 29 examples.
Abstract type: 10 examples.

Total: X examples.
For a full output, updated periodically, see Rosetta Code/Count examples/Full list.

You'll need to use the Media Wiki API, which you can find out about locally, here, or in Media Wiki's API documentation at, API:Query

import scala.language.postfixOps
 
object TaskCount extends App {
  import java.net.{ URL, URLEncoder }
  import scala.io.Source.fromURL
 
  System.setProperty("http.agent", "*")
  val allTasksURL =
    "http://www.rosettacode.org/w/api.php?action=query&list=categorymembers&cmtitle=Category:Programming_Tasks&cmlimit=500&format=xml"
  val allTasks = xml.parsing.XhtmlParser(fromURL(new URL(allTasksURL)))
 
  val regexExpr = "(?i)==\\{\\{header\\|".r
 
  def oneTaskURL(title: String) = {
    println(s"Check $title")
    "http://www.rosettacode.org/w/index.php?title=%s&action=raw" format URLEncoder.encode(title.replace(' ', '_'), "UTF-8")
  }
 
  def count(title: String) = regexExpr findAllIn fromURL(new URL(oneTaskURL(title)))(io.Codec.UTF8).mkString length
 
  val counts = for (task <- allTasks \\ "cm" \\ "@title" map (_.text)) yield scala.actors.Futures.future((task, count(task)))
 
  counts map (_.apply) map Function.tupled("%s: %d examples." format (_, _)) foreach println
  println("\nTotal: %d examples." format (counts map (_.apply._2) sum))
}