What do you mean by merging two accounts? One common inbox for both? There's an existing convoluted way to do that: forward all emails from account B to account A, add account B as a possible "From" address on account A and you're good to go.
I also want to merge accounts, which in my minds means that there really is just one account with several names--emails to all of them go to that one gmail (and it lets me choose which to send from), I can sign into all google services with any of those accounts, etc.
It would be pretty complicated though. I've only used gmail on my secondary accounts, but some people have probably used docs, voice, etc on multiple accounts, in which case all of those need some kind of merging strategy.
You can do that already: I've long fetched mail from two other accounts and any messages I send I can pick which of several e-mail addresses it comes from. "Settings" -> "Accounts and Import" -> "Send mail as:" and "Check mail using POP3:"
This is what I do, but it breaks down when legitimate email ends up in the spam folder in account B. You have to periodically log in to both accounts to make sure you don't lose important emails.
There's a way to fix the spam issue. In the source Gmail account, instead of activating forwarding the normal way, create a filter that will match everything (To: account@gmail.com), and make it forward and not mark as spam.
I do that with only one secondary email that generally wouldn't get any emails from real people, so in most cases, I'm covered. But you're right: that technic should come with a warning: you might lose your emails.
I suppose another way to go around might be to retrieve account B through POP or IMAP.
