Utopia Temple - Probably the most popular Utopia site on the net.  Has a great offline tool called "Angel" and hosts a vibrant online community in its forums. Overall great site. Utopia Pimp - Fantastic site that stores intel data for your kingdom, allowing you to sort enemy provinces by mod def, resources, etc. Get your kingdom to start using this if they aren't already, not doing so would put you at a disadvantage when facing kingdoms that use it.

Glorats - The design is lacking a bit but it was one of the first Utopia site to have online tools.  Their most useful tool now is the warforums (custom forums to use for your kingdom) The World Of Lu Xor - This site has a few interesting online tools, including a province name finder.  It doesn't have any formatters though.

Excalibur - This is a very neat new offline tool that is comparable to Angel.  It is very customizable and is also open source (as far as I know). Utopia Temple - As I mentioned above, this site created Utopia Angel, which is an excellent tool.

Muaddib's Strategy Corner - An awesome guide for Utopia players, great for new players who want to improve their skills or for more experienced players who want to learn something new. Trevor's Guide to Utopia - Offers a complete guide to Utopia, with descriptions of every aspect of the game. Great design, I recommend it to all those new to the game. Oracle's Formulae - A great site for finding Utopia formulas. Similar to Punar's old site, but has some extra features like an offline Utopia Simulator and a few articles. Utopiaways - Another excellent site for people beginning to play Utopia.  It is very in depth, clearly summarizing the guide and also answering many common questions.  Not to mention the great artwork.

Utopia Freaks - Personally I didn't use this site very much but it seemed to have some good online java tools. Silent Hunter has now quit Utopia so this site is no longer active. Utopia Portal - Is no longer being updated. Had some good online formatters and also a few calculators. It's also where I got the idea for the kingdom finder. Punar's Formulas - Used to be a great site with tons of up-to-date formulas, but he is sadly no longer updating it.  However, a lot of his formulas are still accurate so don't be discouraged from checking it out. Starcraft.nu - Used to have some good online tools but it is not active anymore.  It still has a great help section called "Utopia for Dummies" which is excellent for new players.