For example, SQLite is excellent for making an email client. Even on old embedded Arm devices with 64MiB memory, it’s fast enough to handle a gigabyte of messages and an address book with thousands of entries, provided the SQLite DB is located on a good CF or SD card. SQLite is really quite remarkable for the number of occasions where it has been immensely valuable to me and countless others, on such a variety of platforms and in such a variety of circumstances.