Now there are some tools available on the WWW to find more buddies to federate with.
On a personal level anyone could use:
The WCF (who can federate) Tool will scan through your Outlook contacts and give you a "heads up" on which have public Microsoft Lync or OCS federation enabled. This is a great tool to run for people who do or don't have Microsoft Lync to show them who they could connect with in their own contact list.
A system administrator setting up federation could use:
The Get-LyncDNSSRVRecords.ps1 script that takes a CSV list of domains and checks them for _sip._tls.domain.com and _sipfederationtls._tcp.domain.com records and writes the results to a text file.
And as usual you can always check the Swedish Lync Federation List