Constitute.org - “The World's Constitutions to Read, Search and Compare”. Basically a website that serves as a free database of the constitutions of country's around the world, each constitution translated into English. You can read the documents online or download them in .pdf format.
Politic Resources.net - Lots of useful political and politological statistics.
Website dealing with international boundary issues - This is a site for the International Boundaries Research Unit. You can use it to get current boundary info and incorporate it into any current OTL maps that you make.
Rulers.org - An excellent website dedicated to listing all known heads of states of existing and past countries. Also includes lists of religious leaders and leaders of various international organizations.
Regnal Chronologies - A collection of detailed King Lists from every region of the world.
Grey Wolf's Royal Family Trees
Handbook of Byzantine Protocole and Ceremonies, courtesy of Don Giorgio
States and Regents of the World - An alphabetical listing of states and territories and their regents in the 19th and 20th centuries.
List of state leaders by year on Wikipedia
Vincent Ferraro's Terrific Politology Resource Site
Constitution Finder - This database offers constitutions, charters, amendments, and other related documents of nearly every country in the world. Nations of the world are linked to their constitutional text posted somewhere on the Internet.
The Political Graveyard - “The Website That Tells Where the Dead Politicians are Buried”. A little morbid but fascinating website.
The United Nations Homepage - Your one stop shop for every document on every topic you can damn well think of…
Parallel History Project on Cooperative Security - The Parallel History Project on Cooperative Security (PHP, the former Parallel History Project on NATO and the Warsaw Pact), provides new scholarly perspectives on contemporary international history by collecting, publishing, and interpreting formerly secret governmental documents.
The Royal Forums - Discussion board on past and present royals and royal families.
Parliament Diagram Generator - Very useful tool, primarily intended for Wikipedia templates, but generally useful. See this page for Westminster-style parliamentary diagrams.
Political party random name generator - More for fun, but usable.
This page is reserved primarily for general political resources. To find political resources dealing with one specific country, please search the country resource pages.