Given the relative flight velocity between the two birds I would recommend the obvious upgrade to swallows and coconuts rather than pigeons and MicroSD cards. (How had nobody made that joke yet? Honestly, you can't softball it in like that and not be expected to have someone crank the sucker).

But seriously, an unlimited bandwidth 4g solution is probably the most obvious and convenient method. Correct me if I’m wrong but the only problems with that are:

1) No carrier presently offers such a plan (unless you happened to have an unlimited plan prior to Verizon or AT&T's elimination of those offerings);

2) Your post seems to indicate that you want a sans-internet solution, in which case 4g is not for you.

soandos has some helpful ideas, especially with starting the download via remote access so it is finished and ready for transfer by the time you get home. However, all of this seems remarkably after the though and reactive as opposed to proactive.

If you are aware of such large downloads, why don’t you queue them up at night before nappy time and then just bring them into work with you in the morning? It seems pretty unreasonable to think your company would be so impatient to insist on random +500MB downloads but not be willing to cooperate with you working on the files the following day (i.e. have your manager tell you what you need to be working on for the week/day/month BEFORE you come into work any given day)

That solution may seem kind of old school and certainly not as cool as a 4g wireless tether; but hey, capitalists are known for making due with high efficiency and the resources available. Want a promotion? Save your company $3000 a month in upgraded internet costs (what manager wouldn’t love that) and also help your company get a better grip on its POM (process and operations management), and I can almost give you my Cajun guarantee you will receive high marks.