I have been using piracetam and hydergine together for a couple of months now, and I absolutely love it. The piracetam has enhanced my cognitive abilities noticeably in the same manner as bluedolphin suggested, and the hydergine has the additional benefit of balancing my emotions very effectively.
I've also noticed that piracetam enhances stimulants and psychedelics. For stimulants, it makes the buzz feel "cleaner", and the comedowns are much gentler. For MDMA, instead of abruptly dropping off, it slowly fades over a couple of hours. And there's very little drained, depressed hangover the next day. For psychedelics, watch out - piracetam makes them MUCH stronger, primarily in the mental effects. I've had several very profound but extremely unexpectedly strong trips while on piracetam.
And to Mona Lisa, it's subtle. Some people need to take an "attack dose" (3-5 grams) for their first time to get it to kick in. You won't feel a buzz or anything, you'll just notice that your mind is working more efficiently. Some people are used to looking for noticeable and striking effects from substances. Piracetam is not like this. The more in tune you are with your mental state, the more you'll notice it.
And I buy 250 grams of bulk powder for $9.99. That's VERY cheap!