Shallots are small, often no bigger than an elongated golfball and they make a perfect, single portion onion. Their beauty is in their compactness, with no lingering unused portions to manage with though out the week. It's always good to have a few shallots in the single person's kitchen as they store almost as well as an onion and therefore can be easily kept on hand.
As far as taste goes, shallots are reported to be milder and sweeter than a regular onion and for the most part, this is true. This is why a regular onion should be used for a stew or soup where it can offer up enough robustness and flavor to withstand the longer cooking times. A single cook will most likely make up a larger batch of these kinds of dishes (has anyone ever made a single serving of soup from scratch?) and easily use up the whole onion.
The shallot is good for making a vinaigrette, or for sautéing gently as a base for an omelet filling or fritatta. It roasts up nicely with root vegetables and goes well with asparagus, peas and other spring vegetables. It can be used raw, although it isn't always as mild as reported. If you do encounter a strong shallot that you plan on serving raw, I recommend chopping or slicing it and leaving it to sit in some vinegar for at least 10 minutes, maybe even 1/2 hour. This will pickle it slightly and tame some of the strong flavors.
Another mild onion that conveniently comes in small portions is the green onion or scallion. Often, this is this is the onion to use raw, although green onion does work well in a stir fry or other quick cooking dishes. Equally convenient, especially if you have it growing in your herb patch, are chives which are the mildest of the alliums and can be snipped into dishes as a final flourish.
Related: What's the Deal with Shallots?
(Image: Dana Velden)