I myself tried playing round with the site, got the browse button working, the output format selection working. Problem is that it doesn't begin uploading after browsing so better off doing it programmitcally instead of through a website. Makes it less troublesome.
Still want the code for study purposes?
[highlight=vbnet] WebBrowser1.Document.GetElementById("uploadify").I nvokeMember("click") 'Click the browse button
Select Case ComboBox1.SelectedItem.ToString 'Check the choice appropriately according to the com

x
Case "JPEG"
WebBrowser1.Document.GetElementById("fmt_JPEG").Se tAttribute("checked", "True")
Case "BMP"
WebBrowser1.Document.GetElementById("fmt_BMP").Set Attribute("checked", "True")
Case "TIFF"
WebBrowser1.Document.GetElementById("fmt_TIFF").Se tAttribute("checked", "True")
Case "GIF"
WebBrowser1.Document.GetElementById("fmt_GIF").Set Attribute("checked", "True")
Case "ICO"
WebBrowser1.Document.GetElementById("fmt_ICO").Set Attribute("checked", "True")
Case "PNG"
WebBrowser1.Document.GetElementById("fmt_PNG").Set Attribute("checked", "True")
End Select
WebBrowser1.Document.GetElementById("convert").Inv okeMember("click") 'Only works when finished uploading which in this case never happens[/highlight]