There are a number of useful parameters to Twitter's Tweet button that it'd be great to set using the RadSocialShare interface, notably the "via" parameter, which tacks on a related Twitter account to the end of a tweet, as in: "Check out this great site! http://www.url.com/ via @GreatSites", and the "hashtags" parameter, which tacks on hashtags. Available properties are listed here: https://dev.twitter.com/docs/tweet-button#properties.
At least the very used Follow on twitter would be very easy for you guys to include.
As you already extended the Facebook capabilities, I would find very useful you take into consideration to implement points listed in the link referenced above. They did some update on the API (Septembre 2012) and I would find interesting to see, at least,