If you need to upload TIFF files to your site and show the images in browser, then you need to make a browser compatible copy of the file like a JPEG, GIF, or PNG. I whipped up a quick plugin to do just that. When you upload a TIFF file in the media uploader, a second JPEG version of the file will be automatically created. Further, the JPEG version will become the thumbnail for the TIFF, as well as a child post of it. So displaying previews of TIFFs in a theme becomes fairly straight forward.
Generally if all you want to be doing is putting a picture on an article or a page, don’t use a TIFF. But if you actually need to be providing print quality images, for say, a press package, then this cuts your workflow a bit.
You’ll want to increase your upload limit to be able to upload TIFFs, also the plugin requires the PHP extension Imagick. Most PHP installs have it, but if yours doesn’t it won’t install and you’ll wanna go yell at your host.