I think you would agree that with recent introduction of cloud services collaboration has become easier.  Ftp/sftp/scp have become nearly obsolete. Here is a couple of tools that we find useful:

1. Dropbox. This is a cloud file service. The first 2 Gb (which is a lot) are free. An essential tool for sharing projects between group members. Indispensible for  synchronizing files across various platforms, PCs, Macs, smartphones, ipads, etc. Five out of five stars.
2. Mendeley. Bibliography manager. Free. Multiplatform. We share citations and papers (pdf's) between group members; anyone can add and modify references. Mendeley has a convenient option for exporting bibliography into latex .bib file (library.bib). At the moment flaky but still useful. Three out of five stars.