Missing server reference in SharePoint 2010
Unfortunately the "missing server references" health rule in Central Admin Health Monitoring does not display the URL were these uninstalled web parts reside. So to get these pages you'll have to execute some SQL against the mentioned content database. Because this is something that tents to come back regularly on development machines I've created a little SQL script to speed up the process of finding the url's you'll need to delete the web parts.
-- Use the Specify Values for Template Parameters
-- command (Ctrl-Shift-M) to fill in the parameter
-- values below.
USE
DECLARE @className nvarchar = ''
DECLARE @assemblyName nvarchar = ''
SELECT DISTINCT pages.DirName + '/' + pages.LeafName + '?contents=1' as Page
FROM
dbo.AllWebParts wp
JOIN dbo.AllDocs pages on pages.SiteId = wp.tp_SiteId
AND pages.Id = wp.tp_PageUrlID
WHERE
wp.tp_Assembly like '%' + @assemblyName + '%' AND
wp.tp_Class like '%' + @className + '%'
Cheers,
Wes