It's rather difficult to list all the Ho Yay in Gankutsuou. Let's just say Albert has a very blatant mancrush on the Count for much of the series. And that he managed to save the count with the power of a kiss. Under the moonlight.
In episode 14, the scene when the Count offered Albert to come with him in to deep space with him. And the part where he acts like he's leaving but comes back for Albert, walking out to him in the rain, saying he can't bear to leave him alone.
At one point in episode 15, a conversation between Albert and the Count goes thus:
A: "Please stay in Paris forever! Or rather, if that's not possible, let me come with you! I don't want to be apart from you!"
C: "You... care that much about me?"
C: "Passion fades eventually."
A: "That's not true! I... you..." (lit: "Boku wa... boku wa anata ga...")
Very, very blatant. And not to mention the Andrea angle. I bet he has all kinds of talents...
In regards to the Count/Albert relationship, nothing untoward ever takes place (except for an almost-confession by Albert and later a very dramatic kiss in the end, though that was only on the cheek).
Hell, the Count's voice actor said in an interview that he and Albert's voice actor played some of their scenes together as if they were love scenes.
In the opera scene in the first episode where Albert first sees the Count look at Albert's face when he looks at the Count. He's blushing.
Some of the official art featuring Albert and the Count together is very Ho Yay-tastic.
And then there's the fact that Franz is canonically in love with Albert. Even if it's a lie that his seiyuu said so in DVD commentary, it is heavily implied, particularly in the conversation between him and Maximilien. It shouldn't matter that you can't marry the one you love, right?
Franz seemed to be rather self aware when he was young, too. While talking with the Count about his relationship with Albert, he has a flashback of young Albert asking him who he likes, with him responding that Albert "wouldn't understand."
Franz also talks about loving someone even if you can't marry them, while looking at Albert. It's pretty much canon by the end of the series. Franz loves loved Albert, but it was completely one-sided.
And to a smaller extent, it *looks* like Andrea and the Count are going to end up with some sort of dramatic ho-yay, but no. Though Andrea may have 'all kinds of talents' as advertised, he's much happier to go after his own sister. And mother.
Bertuccio is also be implied to be gay and in love with the Count. Even if you disregard his Hard Gay clothing (which might be just for show), he gives the Count a few ambiguous looks. There's also the fact that he throws a rose on the ruins of the Count's base in the last episode, with what might be interpreted as a lovestruck gaze.)