tasks, to-dos and dates; blackberry <--> mac

hi everyone.

i have been wracking my brain trying to figure out a way to have myself organized relatively seamlessly across my blackberry and my macbook pro. i use a limited GTD type system, with a text document of lists by project, and iCal with contexts (work, teaching, etc.) for my dates and appointments.

what i am trying to do is:

-find a way to have what is essentially a calendar and to-do/task list synched to my mac and my blackberry (pearl, soon to be a curve as i want the bigger keyboard).

-ideally i want to do this "over the air", in other words, i do not want to have to plug my blackberry into my mac and do a manual sync (nor use bluetooth, which does not work with OS X anyway) as i will forget to do it every day and its just another step; i want to be able to update something and have it be globally updated. obviously i am assuming some kind of web app is what i am looking for? (google, backpack, etc..?)

- i want to have an offline version so i can see and edit if/when i am sans a net connection; once a net connection does appear, i can manually/automatically update changes either from the BB or the mac. additionally a backup would be nice too.

so i have done a lot of looking around and i cannot seem to find anything/anythings that will do what i want - i assume i am just missing something that is obvious, hence my post. some things that i have noted:

-backpack would be OK for to-dos/tasks; i can also get Packrat as a way to view it offline/backup on my mac, but there is no client i am aware of that runs on the BB to view/update offline on. i do like the backpack style of notes and such. there is also no way to view backpack calendar on the BB.

-google calendar does not allow for offline viewing on the BB, and while i could subscribe to it in iCal for offline viewing on my mac, i cannot edit it in iCal, just view.

so, any ideas? at this point i will concede that i may be forced to do manual syncs with my mac (cable connection, or bluetooth one day in the future) but i would love to find a way to do it over the air. it sounds a lot like if there was a version of Packrat that worked on BB and on mac, and also allowed for the backpack calendar to be viewed and edited that would start to be ideal for what i am trying to do. if it helps anyone's suggestions or ideas i do own webserver space so if there is something else i can run on a server maybe thats the way to go?

thanks everyone!