WordNet (r) 3.0 (2006):

swan song
    n 1: a final performance or effort (especially before
         retirement) [syn: swan song, last hurrah]

Moby Thesaurus II by Grady Ward, 1.0:

124 Moby Thesaurus words for "swan song":
   PS, Parthian shot, Z, addendum, afterthought, apodosis, appendix,
   back matter, benefit, bill, catastrophe, ceasing, cessation,
   chant du cygne, choral service, chorus, coda, codicil, colophon,
   conclusion, consequence, consummation, continuance, continuation,
   crack of doom, culmination, curtain, curtains, death, death song,
   debut, decease, denouement, destination, destiny, doom,
   double take, dying words, effect, eisteddfod, end, end point,
   ending, entertainment, envoi, epilogue, eschatology, exhibit,
   exhibition, expiration, farewell performance, fate, final solution,
   final twitch, final words, finale, finality, finis, finish,
   flesh show, folk-music festival, folk-sing, follow-through,
   follow-up, goal, hootenanny, izzard, jam session, last,
   last breath, last gasp, last things, last trumpet, last words,
   latter end, music festival, musicale, omega, opera festival,
   parting shot, payoff, performance, period, peroration, postface,
   postfix, postlude, postscript, premiere, presentation, presentment,
   production, quietus, refrain, resolution, resting place,
   rock festival, second thought, sequel, sequela, sequelae,
   sequelant, sequent, sequitur, service of song, show, sing, sing-in,
   singfest, singing, stage presentation, stoppage, stopping place,
   subscript, suffix, supplement, tag, term, terminal, termination,
   terminus, theatrical performance, tryout, windup