My husband and I never really sat down and discussed who was going to do what when we got married. For the most part we naturally fell into pretty traditional gender roles. He's always worked full time (or more), second shift for the most part, and I've always worked part time. So while he's has always helped out around the house and with the kids, I've done the bulk of the childcare, day-to day-housework (cooking, laundry, picking up, watering the garden etc.) and overall running of the house (organizing, planning, scheduling, filling out paperwork etc.) for most of our married life.
Every once in a while we get into a small "discussion" over who has more responsibilities and how they should be divided (usually when I'm feeling particularly overwhelmed and/or annoyed that something he said he would do isn't getting done as quickly as I would like it to) but for the most part we just carry on doing the things the way we've always done them.
When the kids were babies we did have an agreement that if we were both home, we took turns changing diapers (which often turned into a heated debate over who's turn it was). He's generally in charge of fixing, maintaining and cleaning our vehicles because he knows a lot more about how they work than I do and he cares more about how they look. I'm a lot pickier about what we eat (and I've always been home more) so I plan and prepare most of our meals. He's much more detail oriented than I am (and probably doesn't hate cleaning as much as I do) so he generally does the more nit-picky cleaning tasks (like dusting, vacuuming and cleaning the fridge, windows and woodwork).
One chore, however, I basically blackmailed him into doing. I really really dislike cleaning bathrooms. I mean really, dirty toilets are so gross. When we'd been married a couple of years I told him that I'd really never intended to marry anyone who wouldn't be in charge of cleaning the bathrooms. I begged, pleaded, whined, pestered and eventually offered to always do all the laundry if he would always clean all the bathrooms. I think he gave in just so I would leave him alone and that's been our system ever since. (Magically this also extends to him cleaning all clogged drains, an even more revolting task than cleaning toilets - win!)
Of course there are occasionally times when he'll do a load of laundry or I'll clean a bathroom (usually if someone's coming over, the bathroom's a mess and he's not here to do it). And sometimes we're so busy that he doesn't get around to cleaning our bathroom for awhile and it starts to bug me. I know better than to harass him about it, and I used to just go and clean it myself if it really annoyed me (which is the grown-up thing to do), but now I've found a better way. Anytime I think our bathroom really needs to be cleaned, I wash our bath mats and hold them hostage. He knows I won't put clean bath mats back into a dirty bathroom and so, magically, without me having to say anything or, more importantly, actually clean any toilets, the bathroom usually gets cleaned fairly quickly. And that's a win for everyone!