*slava "fame, glory" is found in names like Bohu-slav meaning "having the fame of God" and Miro-slav meaning "having peaceful fame". Its cognates can be seen in other branches as well: Sopho-kles meant "famed for wisdom", and Ludwig (Old High German Hlūd-wīg) meant "famed in battle".
And bugger is from the same Latin source as Bulgarian! What does everyone have against Slavs anyway?
Here are the etymologies from the OED, so you can see I'm not making them up.
ad. OF. esclave (also mod.F.), sometimes fem. corresponding to the masc. esclaf, esclas (pl. esclaz, esclauz, esclos, etc.), = Prov. esclau masc., esclava fem., Sp. esclavo, -va, Pg. escravo, -va, It. schiavo, -va, med.L. sclavus, sclava, identical with the racial name Sclavus (see SLAV), the Slavonic population in parts of central Europe having been reduced to a servile condition by conquest; the transferred sense is clearly evidenced in documents of the 9th century.
In early use ad. med.L. Sclavus (recorded from c 800), corresponding to late Gr. σκλάβος (c 580): cf. older G. Sklave, Sclav(e, Schlav(e, MHG. Schlaff. The later forms in Sl- correspond to mod.G. and F. Slave, med.L. Slavus (951), and are closer to the OSlav. and Russian forms: see SLOVENE.
a. G. Slovene (Slowene), pl. Slovenen, ad. Styrian, etc. Slovenec, pl. Slovenci; the name is a survival of the old native designation of the Slavs, which appears in OSlav. as Slovēne, and is supposed to be derived from the stem of slovo word, sloviti to speak.
a. F. bougre: - L. Bulgarus Bulgarian, a name given to a sect of heretics who came from Bulgaria in the 11th c., afterwards to other ‘heretics’ (to whom abominable practices were ascribed), also to usurers. See BOUGRE.