While the composition of some spheres (like e.g. your colleagues at work) is quite straightforward and will not change too frequently, others are somewhat more "lively" - imagine as an example a sphere comprising other researchers working on a similar topic like yourself. In such a case, it is always useful to keep an eye on what is going on, and add potentially interesting users from time to time.
In order to make this easier, we've added "recommended users" to the spheres page (For our power users: This feature will probably remind you of our "similar users".). When logged in, you can find other BibSonomy users which we think might be interesting for you on the top right corner of the sidebar on the spheres page:
Hereby we are computing the similar users mainly based on tag usage - i.e., if other people in the system frequently use similar tags like yourself, we expect that you both share a common interest. Because several similarity measures are hereby thinkable, we've added the possibiliy to choose among them - when you click on the "more" link (see red arrow), you can inspect different recommendations, created by the following metrics:
Although there is an overlap, we expect that the different metrics could be individually useful for finding different kinds of relevant users - empirical studies to this end are part of our research work. In any case, we hope this feature helps you in building great spheres, and finally getting the most out of BibSonomy!