I've had ITB syndrome bad. Use a foam roller, it helped me a ton this past season. Had no pain on a half-marathon and in numerous Olympic distance triathlons. I thought I was over it. Unfortunately, it flared up on the bike portion of an Ironman 70.3 and the 13 mile run was the most painful run of my life, but I did it.

Foam roller was helpful, but after doing some research, this next season I will do a few more things.
1. Foam roller. Damn it is painful at first, but stick with it, use it regularly. It will help.
2. Hip strengthening. I've tried it a little but started too late in the season to make a difference. One study showed relief in more than 20 of 25 within 6 weeks in those who did hip strengthening, with no recurrence. One helpful exercise is to lay on your side, legs together, then raise the top leg up and back down (80s aerobics style, don't forget your leg warmers). This theoretically will strengthen internal hip muscles which helps correct weakness which contributes to knee issues. Also, standing on one leg for prolonged periods is supposed to help.
3. Rest. Unfortunately, once you have it, you have to take it easy and either cut down a lot on training or get full rest. Sometimes this is the worst part when you've worked hard to get a level of fitness.
4. Incremental distance increases. IT is way more likely to occur with suddenly increasing mileage, so if you increase slowly it is less likely to occur.

They say stretching helps, but it didn't help me. Getting my stride analyzed didn't help either, they basically told me my stride was fine with no pronation or inversion. Anyway, I still struggle with it, even though it has improved a lot.

Good luck!