Essential Links

Free Seismic

• USGS - from my uneducated experience, lots of scattered 2D seismic/nav/images.  A little bit of 3D to add a little flavor.
• UTIG - lots of seismic,mainly marine stuff.  Offers a lots more bundled seismic/nav zip files when you put in a request.  Lots of data.
• COCORP (Consortium for Continental Reflection Profiling) - a handful of seismic by US state (that I've looked at so far).

Navigation Stuff

• APSalin - tons of navigational stuff.  Convert this to that.  Stuff to drool over.
• UTM Conversion - this spreadsheet rocks!  A direct link to the spreadsheet brought to you by somebody to University of Wisconsin.
• RCN - Lots of Lat/Long conversions.

Random Virtual Dust (But Very Essential)

• SEG's SEG-Y Format pdf file.
• Wikipedia's SEG-Y entry.
• SLB's Oilfield Glossary - okay.