BTW, the reason why this is "dumb" or "stupid" or "a really bad idea" is that this is better done as a separate table with a foreign key field pointing back to the id field in the first table, a "key" field, and a "value" field. this allows key/value pairs to be individually indexed, searched, and manipulated (add, delete, update).
and even then, this is only useful in some circumstances - where there are a variable number of unknown/arbitrary keys that a given record might have associated with itself. if the name and number of keys is known in advance, there are better ways to handle it.
wikipedia has several good introductory articles on databases and database normalisation that are worth reading. start with Database Models and Database Normalisation