GA-like analytics package that takes unique user IDs?

We're looking for an analytics package fo开发者_StackOverflowr a mobile website. Mobile analytics packages are generally inaccurate when counting unique users because of proxy servers, mobile browsers that don't do cookies, etc. We've come up with good ways of identifying unique users and want to pass a user's ID with each reporting call, but haven't found any hosted analytics packages that will take that ID into account when calculating uniques. There are some open-source packages that let you override their unique ID (Piwik, for one) but we're looking for a hosted solution a la Google Analytics. Does anyone have specific experience with this?

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You can use Piwik on a self hosted server: http://piwik.org/hosting/

This will let you use all Piwik features including Tracking unique IDs

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Infunl (Disclaimer: I am a co-founder) is looking to provide unique user ID as part of backend attributes support to track uniqueness of visitor more accurately. We plan to first offer this for PHP. What backend are you using?