Roughly speaking, there are two broad families of instrument that you're likely to come across when dealing with sampled percussion libraries. The first is orchestral percussion - timpani, snare drum, xylophone, etc - and the other is 'ethnic' percussion, which really covers everything else.
There is quite a bit of crossover between these two worlds in terms of instrumentation, but here we're dealing exclusively with Latin, African and Afro-Caribbean percussion in the context of beat-driven music. Here, then, are some of the most ubiquitous instruments in that category.
Congas
The cornerstone of the Cuban percussion family and a fixture in many forms of dance music - particularly house - congas generally come in sets of two or three (tumba, conga and quinto) and are played with the bare hands. An established repertoire of standard conga rhythms exists, based on the various styles of Latin dance music and serving as a great foundation for your own parts. When you're ready to get into them, we recommend starting at the website of top session percussionist Pete Lockett.
Bongos
Another Afro-Cuban essential, the bongos are a pair of small wooden drums serving a similar role to the congas, although much higher pitched and less 'weighty' in their delivery. Bongos are generally played on their own or alongside a set of congas, the latter option giving the conguero an expansive range of pitches and tones to work with.
Timbales
A pair of single-headed metal drums on a stand, timbales are played with a pair of thin sticks and used for backing riffs (including 'cascara', which involves striking the sides of the shells) and bright, loud, energetic soloing. In dance music, they tend to be called on as a high-impact spot effect.
Timbales and cowbells/agogo bells go together particularly well, and most players will have one or two of the latter mounted on the timbale stand, combining the lot to create intricate, clattering rhythms.
Djembe
You'll see this West African drum in the hands of buskers the world over, the reason being that it can produce both bass and treble notes, making it a sort of self-contained 'one-drum percussion section'. The djembe can also fulfill a similar role to the congas, although it's a lot louder and not as mellow-sounding as its Cuban counterpart.
Cowbell
A clapperless, square-horn-shaped metal bell struck with sticks, the cowbell (and/or a pair of agogo bells) is often found mounted above the timbales, but can also be played held in the hand. Although generally used in rock and pop to rigidly nail the four main beats of the bar, in the Latin context, the cowbell plays the clave or a pattern based around it.
Tambourine
A wooden or plastic ring with pairs of tiny cymbals (zils) mounted within it, the tambourine can be skinned or unskinned, hand-held or mounted on a drum kit or percussion rack. It boasts a variety of uses: it can be used to play a constant rhythm (similar to the hi-hats), for accents (doubling up the snare on the backbeat, perhaps) or as an effect (shaken, for that characteristic shivery sound).
Triangle
The butt of many a percussion-based gag, the triangle is actually one of the most useful 'supplementary' sounds available to the music producer. Whether used for one-shot accents or effects, or to fill out the high end with the kind of rhythm that only a triangle can deliver, it's easy to program and just the thing to bring a funky sheen to any track.
Shekere
Another Latin staple of West African origin, the shekere is a gourd with an open flared tube at one end, wrapped in a cord net with a large number of beads threaded into it. It can be struck, thrown, shaken and 'flicked' (quickly pushing the beads around the gourd) to produce a wide range of tones. Striking the gourd with the heel of the hand gives a rounded, bassy thump; hitting it with the fingertips gives a high-pitched slap; and rapidly pushing the beads backwards and forwards generates a slithery 'shhk' sound. It's one of the more technically involved percussion instruments, not to mention one of the most visually exciting - witness a virtuoso in action…
Cabasa
When a shekere would be overkill, the cabasa steps in to provide a more compact form of friction-based rhythm. The modern cabasa is a wide, short metal cylinder mounted on a wooden handle, with strings of metal beads wrapped around it. It can be shaken to make a rattling sound, or twisted with one hand while the beads are held in place with the other for a similar 'shhk' sound to that of the shekere, but brighter and higher in pitch. Like the shekere, a skilled player can do pretty amazing things with this seemingly one-dimensional instrument.
Shakers
While the shekere and cabasa have their sound-generating beads on the outside, the loosely defined shaker family includes any sealed enclosure filled with beads, as descended from the seed-filled gourd made by that most venerable of percussion manufacturers, Mother Nature. Maracas, caxixi, egg shakers, rainsticks - anything that you shake to mobilise its rattly contents with the intention of providing a hi-hat-like percussion line qualifies as a shaker.
Claves
A pair of thick, short rosewood (usually) sticks, one of which is held with the fingertips of one hand over the 'chamber' made by the palm and fingers (which acts as a resonant space) and struck with the other. The result is a loud, cutting attack, and claves are so named because they're traditionally used to tap out the 'guide pattern' - or 'clave' - in Latin dance music.
Woodblocks
These days a woodblock is as likely to be made of plastic as it is wood, but either way, it's simply a hollowed-out block with a narrow, slit-shaped opening that can be used either as a solitary instrument or in a set of two or more. Fulfilling a similar background role to the cowbell and agogo bells, the woodblock has quite a loud, cutting sound when struck with sticks, so soft beaters are sometimes used instead.
Guiro
Another gourd, this time open at one end with a series of horizontal notches cut into one side. A stick is scraped rhythmically over these notches to create the characteristic and instantly recognisable sequences of short and long sounds essential to several Latin styles.
Agogos
A pair of connected metal bells held in one hand (unless mounted on a stand) and struck with a stick held in the other, agogos have a brighter, less weighty sound than the heavier cowbell, and are a mainstay of the go-go sub-genre of funk (which may or may not have been named after them).
Talking drum
An hourglass-shaped drum with heads at both ends connected by a series of cords that tighten when the 'waist' of the drum, held under the arm, is squeezed, thus changing the tension of the heads and the pitch of the sound. Originally used to send messages from village to village in West Africa, the talking drum is played with a curved stick (held in the free-arm hand) and the fingers of the holding-arm hand, and is loud, attacking and incredibly expressive, capable of blasting out precision melodies and bends over a wide pitch range.
Other
It's impossible to detail the full range of percussion instruments available in just one feature, so we'd urge you to get online and investigate for yourself the likes of the berimbau, cuica, jawbone, castanets, cajon, vibraslap, mark tree, singing bowls and a huge array of weird and wonderful drums from all corners of the globe.
