Note: an alternate cover can be found in the 'nite-bonuspack' collection.
Note that this is for the ancient David Noonan version, not the newer, better version of the track ('brands67').
About half of the covers were done by Don Hodgdon (the modified versions of real-life cover scans), and the other half were done by me (the ones with the hideous early Photoshop experiments... "Bevel and Emboss" for god's sake! Never use "Bevel and Emboss"!)
The map pages weren't necessarily very accurate. These days all maps are done using the GPL Replay Analyzer, so the maps accurately reflect the in-game shape of the track, as modeled by the trackmaker. Didn't have that tool back then, so these maps were often put together using scans from magazines, or random images found on the internet.
These progsets were primarily for the tracks converted from ICR2/CART/N2/N3 by Dave Noonan's converters. The converters were a for-sale thing back in the day, but at some point Dave released them to the public domain. The (now-free) converters still require you to have a purchased copy of the Papyrus game that supplies the track (e.g. NASCAR Racing 3 or IndyCar Racing 2), and those things aren't in the public domain, despite their advanced age. As such, you can't directly download any of these tracks, at least not from Reputable Websites.
Unless you're shooting for a TotalRank, you're not really missing anything if you can't get these tracks. The ICR2 tracks are ugly, and largely ill-suited for GPL cars. The NASCAR tracks are predominately ovals. Many of the more interesting tracks from these conversions have subsequently been built from scratch by various track authors. (ex: Laguna Seca, MidOhio, Portland, Riverside, Sears Point, Watkins Glen, and Indianapolis all have new, downloadable versions available).
Update 02/09/2009 - new map pages, now comes with a PDF.