There's a lot of things that make me notice or want to get to know someone.
1. An interesting signature. This one might be shallow, but if you have nothing underneath your post and someone else has pics, videos, or quotes, my attention is going to be drawn more to the latter. It doesn't mean I won't read what the person without the signature has to say, but it may not stand out as much and is more likely to be sooner forgotten.
2. Sense of humor. I tend to gravitate towards people that have similar senses of humor as myself. The people that I have become especially close with are people that I can just hang around with on skype for hours sending ridiculous pictures and youtube links back and forth. We enjoy being ridiculous and making each other laugh.
3. Quality of character.
Your posts tell a lot about who you are. Some people I'm just not interested in getting to know, not because I'm in a clique and they are not, but because their posts may have led me to believe they are trollish, overly antagonistic, demeaning, or are a liar. There are a handful of people that I have never even personally spoken with but have seen so many distasteful posts from that I just block them rather than waste my time getting upset reading their posts. That's rare though.
However, if you are someone that is kind to to others, offers advise and experience, and knows how to have fun without it being at the expense of someone else, you are probably someone I will want to get to know.
4. How do you converse?
More often than not, when I read posts I look to see if they share similar viewpoints with me. Even if they don't, I like to see how they structure an argument, if its based on reason or emotion, and if they are deadset on being right even if they have to run over or offend others to do that. People that debate politely, intelligently, and evenhandedly are always interesting to me, regardless of the topic or their position.
5 Why are you here?
I also look for people that want to have fun and make friends. Those who make an effort to get to know folks, attend or host local events, or maybe just start a Q&A thread in the silly stuff forum are interesting to me.
I don't have as much time to goof around on the forum as I have in the past, so I may not be as known to a lot of the new people here. But I do still come on pretty daily and look around in a lot of threads. I definitely make note of people I want to get to know when I have a little more time.