Nice social networking is just a social network that caters to a specific target audience. There are social network niches for people into video games, acting, motorcyles etc.
Niche social networking sites can helps because it gives you high possibility to connect with your targeted market. And sharing the same interest.
Here is a list of social niche networking sites that you may find useful.As your question was initially answered i prefer to give you a list of those sites instead.
thegauravkasera in your case, seeing from the links in your signature, a niche social networking site would be something related to vision, eyes issues. Where users could exchange tips and learn things related to glasses, health of eyes and vision in general.