I created a Dropbox account (which I do use) a couple years ago, and last week I visited the site for the first time in almost as long as I've had the account.
A word of warning to you, since you don't access the site often: your password expires, and you'll need access to your email account when it does.
My laptop semi-died last week (it's not actually dead, but I couldn't get it to boot at the time), so I used my girlfriend's to order a new one.
I keep my KeePass database in my DropBox for just such occasions, so I tried to log into Dropbox's web interface to retrieve it and access my account on the computer retailer's website. Dropbox accepted my password, but told me I couldn't continue until I changed my password, which required clicking a link they had sent to my email account.
Unfortunately, the password to my gmail account is also in KeePass, and is an incomprehensible mess of generated gibberish that I don't know, so I couldn't get in. I had to reset my Google password using an email account that is apparently on file with Google, in order to reset my password with DropBox, in order to access my retail account with the laptop vendor.
I don't know if this would have been easier had I known about DropBox's two-factor authentication before this, or if maybe I could have installed DropBox on my girlfriend's laptop and got in that way without needing to reset anything, but I ended up burning half an hour on this because I didn't know I had to keep my password constantly up to date on their website.
It seems like an obvious thing to do, but for something like Dropbox which is just "always there" on your local machine, it's an easy thing to forget.