Heather Morrison suggests that the Directory of Open Access Journals now offers the biggest 'big deal' with, right now, 2996 journals listed.
But is it so? Many of the journals in DOAJ do not fit the model of the scholarly, peer-reviewed journal: for example, in the Library and Information Science area there are journals that are simply the bulletins of professional associations and it is difficult to discover whether or not the contributions are peer-reviewed.
Also, nothing stays still. I checked the eighty journals in the Library and Information Science area and found that thirteen had published nothing in 2007. Of these, two appeared to be completely dead (although one retained the archive of papers) and four had published nothing since 2005.
However, even if this pattern was repeated in other fields (and I suspect that this field might be more prone than others to the optimistic publishing of new journals) and, say, 15% of the journals were inactive this would still leave the DOAJ ahead of the field in the total number of journals 'packaged'. If 'quality' (however we measure it) is taken into account then perhaps another 5% would be suspect, but this would still leave DOAJ with more than 2,300 journals, compared with Science Direct's 2000.
One of the problems is that we still don't have a citation index that covers all OA journals - should SPARC and DOAJ look at that possibility as a further development of the already excellent service?