I love open-source but FME easily wins out against the opensource ETL's as best I can tell. It's actually quite cheap for maintenance and support too (at least compared to most other corporate solutions we have for things).
If you're looking for translations between formats then OGR may do it (with some piping into GDAL for transformations). Of course, that's command line.
For visual modelling beyond those listed in the "possible duplicate" comment, they're working on a QGIS/SEXTANTE model builder; proof of concept video: https://www.youtube.com/watch?v=LTUu-I2ouqU
(No, I don't work for Safe, I'm just a relatively happy customer).