Research treaties gives you a small bonus of research points, which really isn't very effective unless you play with all 9 and get all of their treaties, otherwise you just get like 8 bonus points per turn, when your producing like 100. And economic treaties give you extra cash per turn. (when I say you, i mean whoever is on the receiving end of the treaty, because it is not two way).

Well, I wouldn't say that those treaties are worthless.
I'm about to finish my first game at suicidal where the Drengin were absolurtely superior in every regard during the first year ... beside diplomacy.
About after 1 year we ecchanged research treaties and that must have pumped up my research by ~50% (they had about 4-5 times the research output of me)
After about 1.5 years we made an econ treaty and that one meant that I got 700bc from them per were, when my own tax-.income was just 1900.

beside making friends with the totally dominating force in the galaxy at this time the ecomic value of BOTH treaties probably decided the game to my favour.

Yes, research treaties are not quite worthless, but i will admit, they could or should be a little better. In the example listed above, though, look at it from another angle. Instead of getting 8 TP when you are producing 100 TP, you are getting an 8% boost in research. Thats like having an extra point or two for racial bonuses when starting the game and putting it in research. And over a longer game, 8% is huge.

Research treaties, if acquired at the right time, can really help your empire out. In the early game, get research treaties from as many empires as possible. They're usually in a big financial hole, and will part with these for peanuts. Later, when they're big empires, you get significant research boost. I've had games where I'd set my research slider to zero, because my research was only 30-40% of the total research (the rest coming from the other empires), and I really needed the money elsewhere.

Where this really shines is with minor empires. Unlike the AI, these actually are doing significant research, thus you get a big boost from them. In a recent game, I had eight of these empires in the map, four or so nearby. Each was giving me 20+ research points per turn. My empire at the time, with a 40% expediture, was only able to generate about 30 research points (this was early in the game). Since I couldn't compete, I diverted that 40% expenditure to military production to build more colony ships faster. This let me get a big leg-up on the other empires.

Once you get big, the benefit is much smaller. But getting those crucial techs early on during the planet-grabbing phase can mean the difference between being small and bankrupt with unhappy citizens, and being big, with cash rolling in, and happier citizens. Those early techs are cheap, thus that extra research from treaties can make a huge difference.

So far I have experienced the opposite. Economy treaties are more valued than research treaties. Maybe it depends on the difficulty (playing on normal), or how you are doing in comparison to the AI.

But I agree, treaties are very good for diplomatic reasons. Also, each race can only have one 'outbound' treaty, so the more you get, the less the AIs can establish between them.

The treaties are like 10% I believe. The nice thing about them is they operate like instant trade, improving relations.

Since I play with lots of minor civs, and the value of the treaties generally increases over time, therefore I try to get their research treaties at first contact.

Economic treaties are a great way to snowball an economy that is already highly cash rich (from trade for instance). I'll buy up economic treaties with cash, because it's instant cash in return. Basically it's like buying stock in the other civs.

You only have one of each treaty to give - once you've dedicated your economic treaty to the Yor, for example, you no longer have an econ treaty to offer someone else. Hope that's what you were asking.