Recently we've added two cool features to Songsterr. First one is the "swing feel" support. In songs that should be played with swing feel, each pair of 8th notes should be treated specially. The first note in the pair should be exactly twice the duration of the second note. This kind of playing gives the special groove feel to the music. More on this on wikipedia: Swung Note. To indicate that the song should be played with the swing feel, the special symbol is used in the beginning of the tablature.
The second feature is natural harmonics support. This technique is a bit advanced and it's used by a huge number of famous guitarists (Steve Vai is probably one of the most characteristic harmonic-lovers). You can find good tutorials on how to play natural harmonics on YouTube. Here is one of such tutorials: Natural Harmonics. In tablatures notes that should be played using natural harmonics are indicated by little diamond and the word "Harm." at the top of the staff.
We hope that you'll enjoy these new features. You can listen to the great example, where both of them are used: Pink Panther Theme.