Civilization 2 Design
The Scenario League and its forum. This is probably the best place on the Internet for information relating to Civilization 2 scenario design. The wiki site hosts over 300 scenarios, and many excellent guides and game graphics.
The Cradle of Civilization William Keenan's scenario design site, dedicated to the Test of Time version of the game. It hosts a number of ToT scenarios as well.
Mercator's Civilization 2 Site Loads of utilities (by Mercator and others), maps and technical guides for Civ2 designers.
Civilization Fanatics' Center Largest Civilization fan site on the Internet. Covers Civilization 2, but the focus is on later versions of the Civilization series.
Carl's Scenarios for Civilization II Carl Fritz's excellent scenarios and utilities.
Eyn's World The site's in French. It hosts Test of Time scenarios, graphics, utilities and guides (in French, of course).
Archive of Ancient Civilization A mirror of the Apolyton Civilization Site's Archives sub-forum, created by Codehappy. The threads are unformatted and attachments are missing, but it contains a wealth of Civ2 material.
Scenario League's Civ2 ToT scenario page Hosts more than thirty ToT scenarios by various designers.
Tecumseh's Village Techumseh's scenarios, notably Red October, Operation Market Garden, Warlords of China, Frederick the Great and Roman Civil War. Also hosts Boco's El Aurens 2 scenario and a few FW/MGE scenarios converted to ToT.
I'll toss in a few scenarios converted to ToT using Angelo Scotto's CivConverter:
Indicates graphics modpack available for download.
Civ II Unlimited A launcher for the MGE and ToT versions of Civilization 2, created by Elys. It increases the caps for gold, population and the number of units. It can also extend the time limit in the regular game. Scenario players and designers will be most interested in the new unit maximum (32000, increased from 2048); scenarios with large numbers of units, eg, Red Front, will no longer be plagued by the 'Too Many Units!' message. The download can be found in post #40 of the development thread.
Frhed: The Free Hex Editor What it says. An open source project, released under the GNU General Public Licence. More than adequate for hex-editing Civ2 files.
The GIMP The GNU Image Manipulation Program is a free graphics editor. If you can't afford Photoshop or Paint Shop Pro, you can stop moaning about Microsoft Paint. Now there's really no excuse, is there? You can also check for the latest Windows release here.
Ken Silverman's Utility Page Author of the Build Engine (Duke Nukem 3D, Blood, Shadow Warrior, etc). You can find his PNGOut utility here. Use it to compress your PNG files and at the same time eliminate the troublesome gAMA chunk (a value used by some applications to maintain consistent gamma levels and one that's poorly handled by Microsoft's Internet Explorer). It's a good idea to run this utility on your PNG files before posting them on the Internet.
MastermindX's 64-bit Windows Compatibility Patcher Allows you to run ToT and MGE on 64-bit versions of Windows XP, Vista and 7. It may require further testing with newer versions of Windows. If you have any problems, post in the thread.
PNGGauntlet A nice user-friendly GUI for Ken Silverman's PNGOut utility (see above).
Resource Hacker A utility that allows you to edit 32-bit Windows executables and DLL files. Use this if you want to add custom graphics to Civ2's DLLs (eg, intro.dll, mk.dll, ss.dll and tiles.dll). It's a better option than GIF Xtractor because it doesn't apply the same file size restrictions to your replacement graphics.
7-Zip A free open source archiving program. Can extract the 7Z, RAR and ZIP archives found on this site.
Till's CPU-Throttle A game launcher with the same function as Timbatron's earlier patch (see below), but works with more games, including Alpha Centauri, and apparently even those that use the Infinity Engine, such as Baldur's Gate, Icewind Dale and Planescape: Torment.
Tim's Code Archive Here you can find Timbatron's patched game executables for ToT and MGE. They prevent the game from using all of your available CPU resources. In modern computers this can result in fans going haywire as temperatures soar, not to mention the total waste of electricity. You can thank Tim for his efforts (he doesn't even own ToT) by clicking on his ads.