i can't possibly point out every last moment they've had together through the years-- they have so much history and both characters have been around since before i was born so i can't ever catch up on everything, but i'll mention some of my favorites out of their interactions through the decades.
the beginning's always a good place to start: kitty joins the x-men in uncanny 139 (they didn't have the best initial meeting, as most of you know) and all through 149 (she finally warms up to him in 148) they have some interesting moments. they have assorted moments through uncanny, but nothing major (lots of "katzchen" and "fuzzy elf" ^^ they're too cute, but nothing really focused on them as far as i know). in uncanny 227, we get a hug and some comforting.
the whole of the excalibur 1st series is a must-read (starts in excalibur: the sword is drawn-- lots of nice moments in that special), with plenty kurtty scenes scattered throughout, and just kurt or kitty subplots in general. it's generally my favorite arc of the x-men comics. around excalibur late-40-ish to uh, 70 i think, kurt is with cerise the shi'ar. later on, amanda comes back into his life. from the early 70's to 85-ish, the series is very kitty-focused (illyana's death & subsequent piotr subplot, then rachel and the soulsword...). in excalibur 86, pete wisdom is introduced, and soon he gets together with kitty (i always rather liked this couple... never as much as kurt/kitty, but i always liked wisdom/kitty better than piotr/kitty. i just thought wisdom was awesome. xD lol).
amanda leaves excalibur in the early 100's, if i remember correctly. pete & kitty break up in 120. the 1st excalibur series ends in 125, which is a sweet issue (it's brian & meggan's wedding. kurt & kitty dance together. it's all too cute =3). after that the two (along with piotr) go on a cruise vacation and then rejoin the x-men (uncanny 360 and then x-men 80, they have a few nice scenes there). after a while they each take their own path, kitty goes to college and kurt joins the seminary. piotr's legacy arc is pretty big for both of them. then kitty has a bunch of subplots in different comic series which, TBH, i didn't pay much attention to ^^;;; so does kurt. a particular favorite of mine is exiles 29, when nocturne makes an appearance.
giant-sized astonishing x-men 1 is a must. it's... a big, big one for kitty. and then the divided we stand arc (uncanny 495-500) was a nice one for kurt, especially if you're into male bonding and let's just say, angelina jolie is involved somehow ;) afterward you don't want to miss x-men: manifest destiny 4, which is a gorgeous, gorgeous one. and right there we're caught up to... february 2009, if my memory doesn't fail me. which is... almost 30 years of kurtty, you guys! ^_____________^
my ULTIMATE, ULTIMATE kurtty issues that no shipper can miss:
see, the thing is, i don't generally buy the printed issues. they're hard to come by in my country, especially back when i was growing up, my only access to x-men was through the FOX animated series, and later on when the internet came along i was completely dependent on it for comics. so now i usually prefer to wait to buy the collections on CD/DVD, or lately i download the issues directly from marvel. however, in certain cases there are issues i like so much that i actually go out of my way to buy them in print. to this day, i've bought 4 printed issues. out of those four, 3 i bought because they had kurt/kitty. and i think if you like the pairing, you definitely need to read these issues. they are:
_excalibur 91, "mutants' night out!": team excalibur goes out to a bar to get collectively smashed. kitty and pete wisdom reveal their relationship to the rest. kurt (ok, ok, and brian as well) give pete the "if you hurt her" speech. i thought it was adorable that kurt was so sullen about the relationship, given that he's not usually that... aggressive. ^^;;;
_x-men unlimited 38, "yartzeit": it's been one year since what happened to piotr, and kitty is distraught. she thinks she sees him, and it throws her for a loop. she calls kurt to let him know, he tries to help. eventually kurt comes down to her place and comforts her. it's just too beautiful ;___________;
_x-men evolution 1, "am i blue": one word-- ADORABLE. x3 ok, so it's not actual x-men comicverse but EVOverse, but i still think it's a must-have issue for kurt/kitty fans. truly, closest to canon we've gotten so far in any of the x-men continuities.
_x-men manifest destiny 4, "work it out": kurt is distraught. he's trying to use danger room sims to work some stuff out of his system. but he can't, all he seems to be able to think about is... well, you'll see. needless to be said, this is the most heartwrenching issue i've ever read. oh my god, every time i re-read it it makes me want to break into sobs. i haven't bought this one in print yet but it is absolutely the next one on my list.
so that's about it! i hope you guys find this sort of guide helpful. the x-men universe is enormous and kurt/kitty are just a small part of it, but still it's easy to get lost among all the series, story arcs, crossovers and alternate universes. so hopefully now you'll at least know where to start looking ^___^