Why:
Right now none of them are available in Synaptic on Ubuntu 8.04. There are lots of devises from Polar(1), Garmin(2) and so on that _only_ comes with software for Windows. Perhaps some of them would work with wine, but it would be better if the user out there could get a nice native applications for Linux β with open source. And you don't need a device either, you could use them to track your sporting activities(human Linux users needs some training from time to time:-)
Please vote for this idea if you think Ubuntu should have them ready βinβ Synaptic for new users, even though you don't want/need it yourself.