No, there is no other resource you obtain by trading that is affected by the amount of Cargo ships.
The part of the code that is responsible of getting more titanium with ships is the following:
var shipVal = this.game.resPool.get("ship").value;
var shipRate = shipVal * 0.35; //0.35% per ship to get titanium
if ( this.game.rand(100) < ( 15 + shipRate ) && race.name == "zebras" ){
var titaniumAmt = 1.5;
titaniumAmt += titaniumAmt * ( shipVal / 100 ) * 2; //2% more titanium per ship
this.game.resPool.addResAmt("titanium", titaniumAmt);
tradeRes["titanium"] = tradeRes["titanium"] ? tradeRes["titanium"] + titaniumAmt : titaniumAmt;
//this.game.msg("You've got " + this.game.getDisplayValueExt(titaniumAmt) + " titanium!", "notice");
}
Nowhere else something similar is found in the diplomacy source code.
spoiler about unlocking:
Of course, you'll need 100 ships to unlock the Spider clan!