The most popular dam softwares for now are Portfolio, Iview mediaPro and Fotostation.
I still reccomend people to use a dam software rather than Lightroom in their workflow but some have managed fine with Lightroom an aperture.
You can see my article about workflow and dam at
http://www.benzi.is/?q=node/187
I have now been on the road for over a year and I feel my current workflow is probably the best un til now
I import into lightroom and do ALL the work there (keyword caption and developement)
Then I Import all images into Portfolio and sort them into categories To be worked on.
From Portfolio I keep track of which images have been worked on and which have been sent where and so on.
From Portfolio I open the files in Photoshop and do the final editing and developing of the files.
Having just the laptop and external hard disks this setup has worked fine for me now that I have set up Ligtroom to work the way I want.
Im using Portfolio as I started using it long before Iview came along and it was the best for both Mac and PC. Since then a lot hase changed (and so has Portfolio) and there are more and cheaper options out there.