private void AddImageToThumbnail(string[] images)
{
int top = 0;
int ht = 150;
int counter = 0;

PictureBox[] pictures = new PictureBox[images.Length];

if (images.Length > 0)
{
//The panel pnlThumbnail will hold thumbnail pictures.
pnlThumbnail.AutoScroll = true;

foreach (string image in images)
{
try
{
pictures[counter] = new PictureBox();
pictures[counter].Parent = pnlThumbnail;
pictures[counter].Top = top;
pictures[counter].Height = ht;
pictures[counter].Width = pnlThumbnail.Width - 10;
pictures[counter].Image = new Bitmap(image);
pictures[counter].BorderStyle = BorderStyle.FixedSingle;
top += pictures[counter].Size.Height + 5;

pictures[counter].SizeMode = PictureBoxSizeMode.StretchImage;
pictures[counter].Show();

//If user clicks on a picture then this event gets triggered, it can be used to display the current image.
pictures[counter].Click += new EventHandler(fImage_Click);
pictures[counter].ImageLocation = image;

counter++;
textThumbnailCount.Text = counter.ToString();
}
catch
{
//Error handler
}
}

//Show the first image in the thumbnail
//fImage_Click(pictures[0], null);
}
}


Calling function:
string[] images = Directory.GetFiles(@"C:\Temp\Images\", "*.tif");
AddImageToThumbnail(images);