Terraria has a variety of mods, but I feel that the best one is the Calamity mod.  It is a mod with many new bosses, a huge amount of new items, and a set of inventory addons like a crafting guide,(not the guide) anda boss check list.  My favorite boss is Crabulon.  He drops glowing mushroom related weapons like the mycoroot, fungicide, and mycelial claws.  In expert mode he drops a tresure bag that holds an expert item called the fungal clump.  It is an accesory that summons a flying mushroom crab that attacks enimies and also gives you rapid life regen while attacking.  Calamity is a big mod and adds bosses that come after the Moonlord.