I noticed someone mentioned HP OfficeJet's. I have a J4580, which is not supported under Centos-5.5. (In fact, very few OfficeJet's seem to be supported.)
However, Dag Wieers pointed out that one has to install the latest hplip (together with hpijs and libsane) from http://packages.sw.be/hplip/.
I did this, and find the OfficeJet works perfectly now under CentOS.