To answer a few of the questions in this thread....
- yes, there are Parakleses to many different saints which form a good part of the popular piety among the Greeks. These are generally metered to the original canon in the "small" Paraklesis, though not always. The library of the Monastery of Simonopetra has a large bookshelf with Great Vepers, Orthros w/Polyeleos, Parakleses to saints who do not get such treatment in the Menaion [all of course in Greek]. In the week and a half I was in Greece, I had the opportunity to attend Parakleses, added as a regular part of said church's the regular liturgical cycle, to St. Dimitrios (at said church chanted by the old ladies of the church next to his relics rather than the regular cantors), the Iviron Icon of the Theotokos (at Iviron, again chanted by a 20-something Greek pilgrim rather than the monks, who struggled a bit b/c he was new to the text), St. Mary Magdalene and St. Simon of Simonopetra (at Simonopetra, chanted by the monks - BTW a recording of this is right now available from liturgica.com and I recommend it).
Holy Transfiguration Monastery, I believe, publishes English Parakleses to St. Nektarios (as mentioned), St. George, St. Katherine, and Sts. Joachim and Anna, as well as ones to Our Lord Jesus Christ, your Guardian Angel, or to the Heavenly Powers and all Saints in their Horologion.
- there are usually megalynaria listed in a given Paraklesis (usually but again not always to the melody translated by HTM as "Higher than the heavens" from the small Paraklesis)
- in the cases where there are no megalynaria, I'd do what pensateomnia suggested, ending with "all ye arrays of angelic hosts..."