Where to download USGS DOQQ boundaries? Kevin is correct that some states, Maryland for example, distribute the 12k quarter quad (aka 3.75 minute quad) index for the state. If your study area isn't larger than a few states, you may get lucky that those states distribute the data.
May 7
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Optimize ArcServer Service Drawing Speed Welcome to GIS SE. Additional information such as how many and what type of layers the service contains, as well as how the service is used (as a basemap? for example) by GeoCortex will yield better answers.
How to find lat/lon values for every pixel in a GeoTIFF file? Also, not every GeoTIFF contains a world file. A true GeoTIFF has the coordinate information stored in the header, not in a separate file. However, the term "GeoTIFF" is often applied to TIFF images with a world file. The point is, there won't always be a TFW.