To me a quality face-to-face meeting is the best project collaboration tool.
On several occasions I have worked on projects relying on a purely software environment for collaboration and there was no true sense of involvement there. I felt an air of anonymity and detachment among the members, no shared spirit and consciousness (which allow people to act intuitively and with little direction). Perhaps not surprisingly these projects didn’t fare well.
If you cannot afford frequent live meetings make sure you have a socially competent and engaging moderator to loosen the atmosphere and create situations for people to bond. A woman may be perfect for such a position. For programmers can be so timid and introvert sometimes, and need to nudged 🙂