Hi Willy - i have the same plant and use it in my vaporizer. It is well known to have an effect to vape or smoke lemon balm. It has a energetic up high that is not just placebo.
Now you brought up the subject i mix my weed with a variety of herbs in my vaporizer.
Peppermint:
Gives a very nice taste and that hot/cold feeling you know. It ads a very sweet taste to the vape.
Lavender:
Gives a very pleasant aroma to the vape. Well known for its relaxing qualities. Nice to use before sleeping (putting a fresh branch of lavender in your pillow case is an old days trick against insomnia)
Sage (salvia):
Has some of the same qualities as lavender - lavender i like more because of the most pleasant smell it ads. This is by the way not salvia from mexico that will give you that crazy high - this one is found in many herb gardens.
I just mix these herbs with about half half with weed and it gives me some extra taste variety that i like a lot.
Dried and cured herbs will give you the best aromas.