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.
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 forty 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:
Test of Time Patch Project only. Graphics modpack available for download.
For even more converted scenarios, see the Modified Scenarios Workshop thread in the Scenario League forum, where Gapetit has been very busy.
Civ II Unlimited by Elys. A game launcher for the MGE and ToT versions of Civilization 2. 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.
CPU-Throttle by Till. 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.
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.
PNGGauntlet by Benjamin Hollis. A nice user-friendly frontend for Ken Silverman's PNGOut utility (see above). Supports batch processing.
Resource Hacker by Angus Johnson. 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.
64-bit Windows Compatibility Patcher by MastermindX. 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.
Test of Time Patch Project (TOTPP) by TheNamelessOne. A reverse engineering project that fixes bugs and adds new features to Test of Time, eg, 64-bit Windows compatibility, CPU usage fix, city GUI fixes, global warming fix, no stack kills, invisible health bars, raises money, city and unit limits, increases events memory, and enables the throne room from classic Civilization 2. Highly recommended.