Scale & Warmup Exercises by Bert Casey is a free lesson for bluegrass guitar. These exercises are intended to improve your flatpicking skills.
Most lead bluegrass guitar playing or flatpicking is based on the G scale. You need to memorize this scale.

Once you are comfortable with the G Scale, try this 4 note ascending exercise. This is used in parts quite often in flatpicking. Pay particular attention to the right hand pick direction. It is very important to master the down up picking technique.

After you are comfortable with the 4 note ascending exercise, try the 4 note descending exercise.

Try incorporating these scales and exercises into your playing. You should always warm up before trying to play songs and scales and scale exercises are a great way to improve your technique. Also try playing along with the bluegrass tracks from the Let's Jam CD. These scales will fit almost anywhere.
Improvising with G Licks by Curtis Jones is a downloadable Quicktime video guitar lesson covering some bluegrass guitar concepts. In this video we will learn a series of flatpicking guitar licks in the key of G. We will then learn how we can insert these licks over a jam track of Rolling in My Sweet Baby's Arms. Each lick will be played at two different speeds and then shown in the context of the jam track. Included in the download is a .pdf of the tablature and two .mp3 jam tracks. $4.99