From ProFootballWeekly.com:

With roughly $40 million under the salary cap at their disposal this offseason, it’s no surprise that the Niners have their sights set on more than a few potential free agents, although we hear they still plan on being very careful working this year’s market. Two names that continue to be frequently mentioned on the Niners’ rumor mill are Ravens SLB Adalius Thomas and Bills CB Nate Clements.