I memorized Hamlet's 'To be or not to be...' soliloquy for no apparent reason other than I love Shakespeare and especially Hamlet. It's also neat to be able to quote the whole thing from memory.
I don't know a whole soliloquy, but this exchange between characters always stuck with me in gist and turn of phrase, if not verbatim: Falstaff. I would your grace would take me with you: whom means your grace? Henry V. That villanous abominable misleader of youth, Falstaff, that old white-bearded Satan. Falstaff. My lord, the man I know. Henry V. I know thou dost. Falstaff. But to say I know more harm in him than in myself, were to say more than I know. That he is old, the more the pity, his white hairs do witness it; but that he is, saving your reverence, a whoremaster, that I utterly deny. If sack and sugar be a fault, God help the wicked! if to be old and merry be a sin, then many an old host that I know is damned: if to be fat be to be hated, then Pharaoh's lean kine are to be loved. No, my good lord; banish Peto, banish Bardolph, banish Poins: but for sweet Jack Falstaff, kind Jack Falstaff, true Jack Falstaff, valiant Jack Falstaff, and therefore more valiant, being, as he is, old Jack Falstaff, banish not him thy Harry's company, banish not him thy Harry's company: banish plump Jack, and banish all the world. Henry V. I do, I will.
One of my favorite moments in Shakespeare. I have tried to memorize King Richard II's speech at the end, when he reflects on his life at the end of the play, when he's in jail. But I didn't have the time sadly. I want to try to do it again sometime soon - Richard II is maybe my favorite Shakespeare play. I have various poems memorized, though, and I love to recite them to myself in the shower.
My memory is very poor when it comes to memorising stuff. But that said... I did go out of my way to learn two reasonably sized passages from Julius Caesar, when I was at school. I'm sure it doesn't take too many guesses to figure out which bits. Friends, Romans, countymen... and, O pardon me thou bleeding piece of earth... I just checked and I can still recite them back, word for word, surprisingly enough. I couldn't memorise near so much now. I fear senility is creeping in. Oh... and just I realised, I can remember Cassius': I could be well moved, if I were as you... too. I learnt these 30 years ago, and haven't had cause to recite them since, so I'm actually rather gobsmacked that I've been able to retain them.
I don't know what a soliloquy is, nor do I care, but I have memorized much of Little Women, A Tree Grows in Brooklyn, and Oliver Twist.
Yeah, I have time to think about it, not word for word exactly, but pretty close. It's the most obscure sentences too.