One of the more interesting insert sets in Topps 2009 Series 1 is the 25-card Legends of the Game. The set contains a broad range of Hall of Fame players, from Cy Young to Cal Ripken Jr. The cards have a very traditional look, and there appear to be relic versions of each.
It remains to be seen how popular these inserts will be, when many of these 25 players are also the subject of an SP variation card within the Topps Series 1 Set. As described on bjd610's Topps Blog here, there are 19 SPs in Topps Series 1. Seventeen of the 19 (not including Barack Obama and the Yankees CC Sabathia variation) are also featured in this set.
Thus, the substantial overlap between the two could detract collectors from this set, in favor of the more rare SPs. But this set appears to be a more economical set for Hall of Fame collectors.