Hi,
First off, still loving podcatcher after 3 months of use.
For Honeydew, you face a lot more competition. With that in mind, I think you're going to have to be sure finely tune the UI.
A few things that I don't like about nearly all the other options out there is that they:
a) Sync through the web, to a website that I don't control. The issue here, is how do I guarantee backups, and protection of sensitive information, that may find its way into my lists. I'd much prefer to sync either to my PC, via the blackberry desktop, copying a file, or to have a simple FTP/HTTP interface that syncs to a web interface of some sort, which runs on an open platform: PHP, Perl, etc.
b) lack of a PC companion app. I would love to sort and categorize my lists with drag and drop-ish interface. I also occassionally add a bucket of new tasks at a time on the PC, where I have a bigger keyboard.
There are some things that I would find cool, but I do not consider essential:
a) Strong integration with URLs (I keep a list of URLs that I don't have time to finish reading at the moment, but want to finish later).
b) Strong integration with blackberry emailing and calling, so that I can just click on the phone button when the cursor is over the phone number, like in the default blackberry task manager.
c) Easy switching between category views, and moving tasks accross categories, on the blackberry. The default task manager works, but is a bit clumsy.
d) encryption of tasks over the internet when syncing would be nice, but not a big deal.