Seconding Arvo Part, Spiegel im Spiegel and Tabula Rasa are pieces I know and love.
Shostakovich String Quartetts. Nr. 8 is amazing.
For violin things, check out Sarasate (tarantelle and Zigeunerweisen) and Wienawski (Legende, and concerto 2) as well as Anne-sophie Mutters rendition of Tartini's trillo diablo, the third movement.
Those who like atonality might be interested in this: https://www.youtube.com/watch?v=XJ37gYu5tKg
(penderecki etc. goes without mention I presume)
Liszt needs a mention, for his piano work (check out his rewritings of paganini caprices). Ditto chopin.
I love big pompeous Opera pieces. William Tell, Norma, la Zingarella, Va Penziero.>>5972
More Williams: https://www.youtube.com/watch?v=UD39DV1A02s>>5966