[kareemamin]

endor.se looks very interesting. We may consider the ability to enter any site you want and we'll try to grab the fav icon for it, so we can show it nicely in the signature.

[kmfrk]

Sounds like the best way to approach it.

Only the basic services are necessary, as they give people an idea of what the service can be used for.

A laundry list of service icons in your signature also gives a slightly ... weird impression. :)