Without sounding like a prat...

There are few routes to one of the Big 5 (if that's the level you're going for) that doesn't involve an agent. Your cover in your avatar seems to indicate you write one of the subgenres of romance or erotica. Harlequin still takes direct subs from authors and so does Tor (where I'm at.) But Tor generally does only paranormal romance. For Small Press (print) I think Sourcebooks Casablanca is still accepting direct subs. They've become very well respected, with a fair number of USAT and NYT authors.

I'm a fan of agents and would strongly recommend that route if you want to get to the next level where you're not your own publisher--and not everyone wants to be, myself included.

Good luck!

It does sometimes happen but I wouldn't bet on it. Because if you were an editor at a small imprint, and you came across a really good book, would you say to your bigger brother, "hey! here's a really good book! do you want it?" or would you sign it, and enjoy the sales it produced?

What you need to move up a step is a good agent. If you're struggling to find one then it's likely that either your work isn't good enough, there's a problem with your query, or you're not submitting to the right agents. You might like to put some work up in our Share Your Work rooms and see what feedback you get: it can really help.

Good luck!