A few readers have emailed me recently about rice cookers by coincidence. So I thought I would put my answers here for everyone’s benefit.
A single portion of rice ranges from 1/2 to 1 cup. So, if you are a single person or a couple you don’t need a huge rice cooker unless you are the social type who regularly has parties. The smallest capacity I’ve seen sold outside of Japan (where they do sell 2-cup or even 1-cup cookers) is 3 cups.
However, the newer rice cookers from good manufacturers like Zojirushi, Panasonic, Mitsubishi and so on handle small amounts of rice in their big-capacity rice cookers. For example this 10 cup capacity Zojirushi model  can cook 1 cup as well as 10 cups. So, the size issue may come down more to budget and how much countertop space you can give it.
My general philosophy is this: If you think you’ll use it regularly, it’s worth spending a bit more for any appliance. The if you’ll use it regularly part is critical though. Will you be making rice at least 1 or 2 times a week, every week? Then a rice cooker is worth getting. And there’s such a world of difference between a good rice cooker and a cheap one. The most important one is durability - my older Zojirushi rice cooker is 20 years or so old and still working fine. The more durable an appliance is, the less you’re going to be adding crap needlessly to your local landfill. And you’ll save money in the long run.
(Incidentally, I’m not being unfairly biased by always recommending Japanese rice cooker manufacturers like Zojirushi. For one thing, everyone in my family has had great experiences with them. For another - Japanese people eat a lot of rice and they are quite particular about how their rice cookers perform!)
Again, if you think you will be cooking other types of grains or rice regularly, definitely yes.
In order of importance:
If you’re cooking Japanese style rice, are you sure you got the right kind? (See Looking at Rice .) Are you washing it correctly? (See How to wash and prepare rice .) You can’t skip the washing part and expect to get rice that’s as good as you can get at your favorite Japanese restaurant. (And to be picky, a lot of Japanese restaurants don’t wash their rice well enough for me, or use the evil ‘no-wash rice’ (musenmai). But that’s another story.)
You sure can. You have to keep in mind that a rice cooker is designed to start cooking at a low heat, gradually increasingly the heat, ending at a high heat. And it’s also fairly (in some models completely) sealed, so you get a moist steam heat. So, things that can be cooked in that type of environment will fit. There are several books about rice cooker cooking in Japan, and All About (the Japanese equivalent of About.com) has a whole section devoted to the subject . There are some rice cooker books in English too, like this one . I can’t vouch for any of the books, but I’ve tried some of the recipes on All About and they are rather fun.
Our ancestors didn’t have cute beepy electric cookers, so obviously it is possible to cook rice properly without one.
I have a little confession actually - recently, I’ve been cooking rice more and more in anything but my rice cooker. I still rely on it when I’m in a hurry. And when someone else is making dinner, I can just ask them to ‘do the rice’ and as long as it’s using the rice cooker, everything is ok.
But I’ve found that the best tasting rice really is made in a regular, heavy pot, or in a pressure cooker. That’s the only way I cook brown rice  these days. However, it takes some patience and practice to cook rice without the handy set-it-and-forget-it-ness of a rice cooker. I never used to be able to cook rice properly without a cooker - the rice would always turn into mush, or be hard and raw. Even now, after years of fairly concentrated practice, I occasionally turn out a pot of inedible goo.
So for a busy person who cooks a lot of rice or other grains, I think a rice cooker is a great appliance to have. It’s just one less thing to think about after all.
One very important thing to keep in mind if you purchase a rice cooker is that you should always use the little measuring cup that comes with it. The capacity of the cup is usually 180ml, which is less than a Japanese one cup (200ml) or an American one cup (236ml) or the offical metric one cup (250ml). If you do lose that cup though, just measure out 180ml with a regular measuring cup.
Europe-based readers haven’t had a lot of luck finding Japanese rice cookers, barring a trip to Japan. I’ve spotted this fairly new Zojirushi Rizo model on the web site of a German/Japanese mailorder store, Ja-Mart:
It’s a 3-cup capacity model that cooks Japanese style rice, risotto, and also does ‘steam cooking’. It comes in yellow, white and stainless steel, and it’s available from Ja-Mart.de . The price for the yellow and white models is €186, which for a Japanese rice cooker in Europe is fairly reasonable. The site is in Japanese and German only, but they do deliver to several European countries, so try emailing them at customer.service at ja-mart dot de. (Note for people in Switzerland: they do ship here, even though Switzerland doesn’t appear in their drop-down menu.)
If you’re in the U.S. and fall in love with the cutie, you can get it from Amazon .
(Update on JA-Mart: They now carry a 1 to 10-cup capacity IH (Induction Heating) rice cooker from Tiger , another very good brand.)
CasaBento  carries 220v models of Zojirushi rice cookers. For example this Zojirushi 5.5 cup model  is €144.99; in the U.S. it retails for $164.99 on Amazon.com . If you know anything about U.S. vs. European prices, you’d know that that makes the CasaBento price pretty fair. (Disclaimer: As of October 2009, CasaBento is a premium advertiser on Just Bento.)
I received an email from Donna and Neil of Yum Asia , who currently sell two models of Zojirushi Fuzzy Logic rice cookers in the UK. They are 220-240v and have three-pin UK plugs (an adapter plug would be needed for continental Europe). Check them out!