cogadh: Or use the portable version of FF3 on a thumb drive so that you bring the cookie with you to whatever PC you are using.
Honestly, I don't think it will make a difference when the site goes live, it is still going to require some kind of login to access all its features when it is out of beta, so you will still be in the same situation.
BTW - How does FF crashing delete the cookie? I've never lost any of my saved cookies when it has (rarely) crashed on me. AFAIK, the only way that can happen is if you have FF configured to delete cookies when it closes.
Actually, I used to have the problem that my Firefox would delete all my cookies whenever I restart my browser (or my computer, I ferget). I found out from a solution posted online that my cookies.sqll file or something like that got corrupted. I just deleted it and it's been working ever since.