Keeping your feet dry (or do you not even care?)

Don't care too much.

Aside from very long rainy rides, wet feet aren't too bad unless you also have to deal with low temperatures. In that case you have to have booties to cover the feet to keep them from getting wet in the first place.

I have some pairs of "smartwool" cycling socks. They're thin enough and durable for cycling. When it rains, your feet still get soaking wet but they dry out fairly quick, and are slightly more comfortable than regular cycling socks (which really aren't too bad either). Cotton socks would mostly likely be a very bad idea.

The shoes, I think, are just as important. Sidi's tend to be very porous so they drain well. I don't know if other shoes also drain well. If not, they're probably not good for wet weather and cycling in general.

When it's really cold or really wet, I wear water resistant shoes. Some sort of cover over your shoes would be good instead. (make sure the water resistant pants go down to the shoe so you don't fill the shoe with water via your ankles)

When it's slightly wet but not that cold, I wear wool socks. Actually, I wear wool socks all through summer, too. I'm more likely to wear the almost invisible ("micro" height) ones during summer and ones that cover the ankle a little ("mini", "half crew", "3/4 crew") during cooler weather. I find that wool socks keep the feet reasonably comfortable if there's a bit of moisture. In heavy rain where there's significant water flow through your shoe nothing is going to help because the water is being replaced with cold rain water too fast.

Note that the type of wool does matter. Merino is more expensive but less itchy. I believe the longer fibers in merino may make it easier to make thinner socks, too. Make sure it's not acrylic, which can look and feel a lot like wool but doesn't have the wicking or antibacterial properties.

As far as where to find wool cycling socks? Check at your local cycling stores first. Also check at outdoor stores since summer hikers often like thin wool socks that don't go up the ankle too. Shoe store or running store might also have something.

The brand I usually wear is Smart Wool, like these socks. I've seen wool socks intended for cycling from: Sock Guy, DeFeet, Capo, Castelli, Endura, and others however. They don't necessarily have to be specifically for cycling, any thin merino wool sock that fits well should work so a "running" or "casual" sock could be just fine.

If it's cold, it's really not much fun having wet feet.

In the summer, I use either some GoreTex trainers or SealSkinz waterproof socks for when it's raining. I really like the Sealskinz. One time the heavens opened just before leaving work and only had sandals, but then found the SealSkinz in my bag - that was almost perfect, warm, dry feet and no shoes to dry out once home.

In the winter (lots of snow in Helsinki), I wear normal winter boots to just above the ankle, which are also waterproof.

Merino socks are very good, I have some SmartWool ones. You can get SealSkinz with merino as well.

Here in Portland where we have months of cold and rain I typically wear wool socks and leather boots for my commute. In the past when I've worn cycling shoes I would wear a low-cut wool sock and neoprene booties. In our climate this serves me for the whole rainy season.

Usually I don't care about my feet getting wet, as long as I'm not cold. If I'm commuting to work, I just pack extra socks so my feet aren't wet all day. If I'm out for other purposes (exercise, recreation, etc.) then I'll just change when I get home. Same reason I avoid fenders. I am very rarely in a situation where I care if I get wet.

This may be unthinkable in some cultures (esp. English-speaking ones), but a time-tested and easy solution is to take off the shoes and put them in your bag until it stops raining.

As DavidW points out, it may be uncomfortable when it’s cold and windy on top of rainy, yet not so cold that it’ll just snow instead of raining. To me this seems such a rare confluence of factors you can just put plastic bags over your shoes when that happens.

I live in a tropical country, so most of the year the temperature is above 20° Celsius, so coldness is not an issue here. It can also be unpredictable for rain.

I have tried both strategies: a) (try to) keep dry while riding under the rain and b) (act like) not caring about it.

With strategy a, the problem is sweat accumulates inside rainproof gear, so I end up as if had worn no rain gear at all.

With strategy b, it's all about what waits for me at the end of the ride. When I start and end my rides from my car or home, hotel room, etc, I just leave a second clothes change there, including socks and footwear. If that's not the case, I carry a light jacket and just wear it even on top of my soaked jersey after the ride. That is because for me the severe cooling of the jersey causes me a severe cold (as in sneezing, coughing, etc...). That works for me because I would remain on wet clothes for a couple of hours before having access to a warm shower and dry clothes.

If I had to commute under rainy conditions, I'd just roll a change of office clothing and an extra pair of shoes. When commuting I always aim to arrive with time to spare so I can go to a toilet stall to freshen up and change clothes, no matter if wet from rain or from sweat.

Regarding shoes specifically, I use MTB biking shoes that usually have breathing fabric on the sides. They get soaked to the point water spews out on every step or pedal stroke. I just don't care. Fungus does not develop "under water" so as long as I do not remain on wet shoes/socks for too long, there is no problem at all.

When circumstances allowed and I had to use the shoes next day, a hair drier works wonders. Also useful for socks and other small items.

Other times, for short rides (4 hours or less) I just did wear them as is and washed and dried them afterwards. It is awkward when you put them on, but as soon as the water in them reaches the same temperature as your feet, you barely remember they are wet.

I prefer to wear tight clothes that move with your skin, rather than loose clothing that rubs against it. Heavy rain has caught me riding with baggy "surfer" shorts and the wet fabric dragging on my thighs where a huge waste of energy, specially at the end of a tiring stage on a multi day ride. Also the wet clothes caused severe chauffing on the inner leg, near the groin. However, when using proper cycling shorts, even under heavy rain, I had no problem at all.

The same applies to shoes, I prefer to have them as tight as necessary so they do not rub against my skin. Constantly rubbing the wet skin with force and wet fabric is a recipe for blisters. As i said, my shoe's material is very breathable.