I'm looking for a web application that will update my Google Latitude location every time I update my Yahoo Fire Eagle location. I checked the Fire Eagle application gallery and didn't find anything that would do this.
For anything that requires cross-app integration, I use IFTTT which stand for IF This, Then That. It allows you to create recipes which are basically a set of actions consisting of a Trigger and an Action (to be taken on Trigger) for Channels which are apps that it supports (like Facebook or Gmail or WordPress or Date and Time, you get the idea).
FireEagle -> FourSquare
FourSquare -> Latitude
While IFTTT does have a for FourSquare, it doesn't for Latitude, so it can't be of any help. After Googling, I found this post which tells you how to connect the two.
If that doesn't work, you can use IFTTT, though in a different way. You can use the FourSquare Channel to output the check-ins to a text file in Dropbox or a message in Evernote, from where you can search for integration into Latitude.
List of Channels
While isn't relevant to your question, I am proud that I came up with the code to extract this within 20 minutes considering I'm a newbie to JS:-
For a full list of IFTTT's currently supported channel, here you go:-