I'm in love with 37 Signals products, use Tada List frequently, and am interested in Highrise for my job.
I have to find a database to keep track of all the people involved and the money that goes to them, and what's do when in terms of their/our agreements, payments, follow ups, etc. I just don't think Highrise is the right thing for us. The tag/case feature, from what I could tell, allows for putting individuals in multiple categories (i.e., geographic location, organization) but it does not look like it's at all capable of a friendly relationship with snail-mail-merge mass mailings, or pulling up groups of individuals and organizations based on specific pieces of data. Also I don't think there's an option to add fields (for example, "amount of grant", "date awarded", "date of evaluation received").
Such things would require a complicated data export to something like Excel or Access which would defeat the purpose of having the system to begin with, from my point of view, and learning new software secrets which I routinely avoid. It's also a little expensive.
It's hard to explain why but it's really difficult to find a database-contact-management-system that is right for this organization, other than Access. But my charge is to get something that's not Access. So oh well. Most of the stuff out there for non-profits is about raising money but I want one that is about giving money away.