Funny that I never felt the same way like Aiwass. I used to play lot of chromatic stuff (now I do it little less but I can reach about 250 whenever), but chromatic scales get pretty boring and you don´t need to think and focus as you have to when playn´ 3 notes per string. You need to think about down-up-down and than next string up-down-up but most off all finger position changes. I found 3-note per strings scales on the site by a guy called Schmange (somthing like that) and not that I only play them normally, I have trandform them into string skipping so that I play 3 notes on E, 3 on D, than 3 on A and so on. It´s pretty cool. Another verision is to skip E-E, A-B, and D-G string (the last isn´t a skip). This is pretty rough cause of wild finger position changes but is very good for cordination.

Another thing that John Petrucci uses frequently:

e-14-15-14-12-----------
B-------------------14-12--

Play it in the 16-note triplet fell (14-15-14) and than (12-B14-12). All with pick of course. Maby you all ready know this lick but the point is that it´s good for cordination and than there are hundreds of combinations to do it.