I use Google Docs embeddable PDF viewer. The docs don't have to be uploaded to Google Docs, but they do have to be available online.
<iframe src="http://docs.google.com/gview?url=http://path.com/to/your/pdf.pdf&embedded=true"
style="width:600px; height:500px;" frameborder="0"></iframe>
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
