My ISP, for one, uses transparent proxies.
Sir Thomas Beaufort, afterwards earl of Dorset and duke of Exeter (appointed admiral of the fleet 1407, and admiral of England, Ireland and Aquitaine 1412, which latter office he held till his death in 1426), certainly had a court, with a marshal and other officers, and forms of legal process - mandates, warrants, citations, compulsories, proxies, &c. Complaints of encroachment of jurisdiction by the Admiralty Courts led to the restraining acts, 13 Ric. II.
This instrument, which was designed to replace the Concessions, provided for the government of the province by a governor chosen by the proprietors, a common council consisting of the proprietors or their proxies together with 12 freemen, and a great council consisting of the proprietors or their proxies together with 144 freemen chosen by a mixed system of elections and the casting of lots.
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In addition to eBuddy Proxy, there are numerous other web-based proxies such as Proxify and Anonymouse.