SharePoint Picture Libraries create thumbnail and preview jpeg images from Tiff files.
To render the preview image in a Data View, add the following after the <xsl:stylesheet line near the top of the web part
<xsl:param name="HttpHost" />
Then to display the preview image in the rowview template, use
<td class="ms-vb">
<xsl:variable name="PreviewURL" select="concat($HttpHost, ddwrt:UrlDirName(string(@FileRef)),'/_w/',ddwrt:UrlBaseName(concat($HttpHost, @FileRef)),'_', ddwrt:GetFileExtension(concat($HttpHost, @FileRef)),'.jpg')" />
<img src="{$PreviewURL}" />
</td>
Tiff images in this demo came from http://users.ugent.be/~avierstr/ and are stored in this library http://www.wssdemo.com/tiff