I gave R2admb a test run and found it quite promising. The design is simple: to have a simple interface between R and ADMB so ADMB can get input from R and can send output back to R for further processing. This does not eliminate the trouble of writing a TPL file, but makes everything else much simpler. I hope this package gets polished and get into CRAN soon. I am sure it will help more people to get to know ADMB in the same way as R2WinBUGS help people use WinBUGS and R2jags help people use JAGS.