Besides just playing chords or individual notes with your left hand while rolling with the right, you can also add in special effects such as Hammer-ons, Pull-offs, and Slides. Here are some basic hammers and pulls you can do in G-tuning. You pluck the given string either open or fretted, and then, without plucking the string again with your righthand, use the left hand to make an additional note by either hammering or pulling.
(If you'd like some more info on hammers or pulls, check out the general techniques page since these can be done on most fretted instruments)
Here is a good exercise to get your ear attuned to the sounds. It almost sounds like a melody.
I encourage folks to play around with these until they get some exercises they really like to do.
Here are some special effects inserted into a basic forward roll.
The first two start with a hammer-on on the 2nd string but they differ in their timing. In the first, the second note of the hammer hits exactly at the same time as the second note of the roll. In the second example, you hammer quicker and get a separate note before plucking the second note of the roll.
They are exactly the same except for the timing of the hammering motion. There are all sorts of variations you can make this way.
The final example is a pull-off that doesn't have a second note plucked by the Middle finger.
All the examples so far have used hammers and pulls to open strings. You can also hammer and pull
to and from fretted ones.
The first example below is just some exercises. The next two are forward rolls with a hammer from or pull to a fretted string.
Here are some of the common slides used on a banjo.
You start on the first note and slide up or down to the next one sounding out (quickly) the other notes in-between.
Below that are some forward rolls using slides.
Tuning notes are the notes you use to tune the strings to.
Fretting a tuning note and playing the next string up open gives you the identical note in two different places.
These are used to emphasize certain notes.
Here are some examples using those.
Many of the examples use the Forward Roll.
The ones that don't use the Alternating (or Back and Fort or Square Roll) where you just alternate between Thumb and Finger.
These examples don't use the actual tuning note but the one just below it to make a more bluesy sound.