Nowadays, mail-order printed circuit boards (PCBs) cost as little as $2 a piece. Using surface-mount parts (SMD) tend to be compact, abundant, and about as easy to use as through hole parts.
lcamtuf’s thing takes a look at using surface mount parts to include the dizzying variety of surface-mount package sizes. In the world of through-hole components, almost every part has a familiar footprint. When it comes to SMD, DigiKey stocks about 100 different form factors for resistors alone.
Passives and friends
Many small, two-terminal components — from resistors, to ceramic capacitors, to LEDs — come in rectangular packages in a 2:1 aspect ratio, with solder terminals along the shorter edges.
Integrated circuits
Many chips with low pin counts — including most op-amps and 8-bit microcontrollers — are available in rectangular SOIC or SSOP / TSSOP packages with pins arranged along the two longer edges. Integrated circuits with higher pin counts, including some 8-bit and most 32-bit MCUs, might also come in square packages leads on each side; these devices are designated as QFP, TFQP, or LQFP.
Other components
Some components, such as power inductors, connectors, switches, or discrete transistors, will have different packages; only some of these are standardized.
See how each of these are handled in the excellent post here.
Also see our post The ultimate SMD marking codes online database