diff --git a/inc/admin.inc b/inc/admin.inc
--- a/inc/admin.inc
+++ b/inc/admin.inc
@@ -146,12 +146,13 @@ function school_cache($schools)
 	  foreach ($school['crawled_semesters'] as $semester)
 	    {
 	      $semesters[$semester->id()] = array(
-						  'id' => $semester->id(),
-						  'time_start' => $semester->time_start_get(),
-						  'time_end' => $semester->time_end_get(),
-						  'weight' => $semester_weights ++,
-						  'name' => $semester->name_get(),
-						  );
+		'id' => $semester->id(),
+		'popular_course_id' => $semester->popular_course_id_get(),
+		'name' => $semester->name_get(),
+		'time_start' => $semester->time_start_get(),
+		'time_end' => $semester->time_end_get(),
+		'weight' => $semester_weights ++,
+	      );
 	    } /* foreach ( => $semester) */
 	  /*
 	   * Store/cache the semester metadata:
diff --git a/inc/class.semester.inc b/inc/class.semester.inc
--- a/inc/class.semester.inc
+++ b/inc/class.semester.inc
@@ -80,6 +80,11 @@ class Semester
 
     $this->departments = array();
     $this->department_names = array();
+
+    /*
+     * For $this->popular_course_get().
+     */
+    $this->course_num_sections_map = array();
   }
 
   /**
@@ -89,22 +94,26 @@ class Semester
    * \param $class
    *   The class/course to add.
    */
-  public function class_add(Course $class)
+  public function class_add(Course $course)
   {
-    $class_parts = Course::parse($class->getName());
-    if (!isset($class_parts['course']))
-      throw new ErrorException('I was given a class with an invalid name: `' . $class->getName() . '\'');
+    $course_parts = Course::parse($course->getName());
+    if (!isset($course_parts['course']))
+      throw new ErrorException('I was given a class with an invalid name: `' . $course->getName() . '\'');
 
-    foreach ($class as $course_slot)
+    foreach ($course as $course_slot)
       foreach ($course_slot as $section)
+      {
         foreach ($section as $meeting)
           $this->time_set_section_meeting($meeting);
 
-    if (!isset($this->departments[$class_parts['department']]))
-      $this->departments[$class_parts['department']] = array();
-    $department =& $this->departments[$class_parts['department']];
+        $this->_section_count($course, $section);
+      }
 
-    $department[$class_parts['course']] = $class;
+    if (!isset($this->departments[$course_parts['department']]))
+      $this->departments[$course_parts['department']] = array();
+    $department =& $this->departments[$course_parts['department']];
+
+    $department[$course_parts['course']] = $course;
   }
 
   /**
@@ -244,6 +253,8 @@ class Semester
       }
 
     $classobj->section_add($section, $course_slot_id);
+
+    $this->_section_count($classobj, $section);
   }
 
   /**
@@ -299,6 +310,46 @@ class Semester
 
   /**
    * \brief
+   *   Account for the addition of a new section to this Semester.
+   *
+   * \param $course
+   *   The course this section is a part of.
+   * \param $section
+   *   The section.
+   */
+  private function _section_count(Course $course, Section $section)
+  {
+    $fully_qualified_course_id = $course->getName();
+    $this->course_num_sections_map += array($fully_qualified_course_id => 0);
+    $this->course_num_sections_map[$fully_qualified_course_id] ++;
+  }
+
+  /**
+   * \brief
+   *   Get the most popular course.
+   *
+   * \return
+   *   The fully-qualified course_id of the most popular course in
+   *   this Semester.
+   */
+  public function popular_course_id_get()
+  {
+    if (count($this->course_num_sections_map))
+      {
+        arsort($this->course_num_sections_map, SORT_NUMERIC);
+        reset($this->course_num_sections_map);
+        $this->_popular_course = key($this->course_num_sections_map);
+      }
+    if (!isset($this->_popular_course))
+      {
+        /* The default popular course */
+        $this->_popular_course = 'ENGL-101';
+      }
+    return $this->_popular_course;
+  }
+
+  /**
+   * \brief
    *   Update the time_end.
    *
    * The time_end is a unix timestamp roughly estimating the time at
@@ -527,5 +578,14 @@ class Semester
     $this->time_ends = array();
     $this->time_start_get();
     $this->time_starts = array();
+
+    /*
+     * A mapping which keeps track of how many sections any given
+     * course has, with course_id '-' section_id as the key and the
+     * count as the value. Used to calculate the most frequently-used
+     * course_id to use as the example course_id (bug #102).
+     */
+    $this->popular_course_id_get();
+    $this->course_num_sections_map = array();
   }
 }
diff --git a/input.php b/input.php
--- a/input.php
+++ b/input.php
@@ -114,8 +114,10 @@ elseif (!empty($_REQUEST['e']))
 $inputPage = page::page_create('Enter Courses', $scripts, $inputPage_options);
 $school = $inputPage->get_school();
 $semester = $inputPage->semester_get();
+if (empty($semesters))
+  $semesters = school_semesters($school);
 
-$my_hc = 'var slate_permutate_example_course_id = ' . json_encode(school_example_course_id($school)) . ';
+$my_hc = 'var slate_permutate_example_course_id = ' . json_encode(empty($semester) || empty($semester['popular_course_id']) ? school_example_course_id($school) : $semester['popular_course_id']) . ';
 
 jQuery(document).ready(
   function()
@@ -270,7 +272,7 @@ if (!empty($_REQUEST['selectsemester']))
   Welcome to SlatePermutate<?php $inputPage->addressStudent(', ', '', FALSE); ?>!
   <?php if (school_has_auto($inputPage->get_school())): ?>
   To get started, enter in a course identifier (e.g., <em>
-  <?php echo school_example_course_id($inputPage->get_school()); ?></em>)
+  <?php echo empty($semester) || empty($semester['popular_course_id']) ? school_example_course_id($inputPage->get_school()) : $semester['popular_course_id']; ?></em>)
   and click the autosuggestion to automatically load available sections
   for each class.
   <?php else: ?>