Our Gemara mentions that the ketores incense is a segulah for becoming wealthy. Even today, there are those who read the ketores from parchment so as to come as close as possible to fulfilling this mitzvah (Kaf HaChayyim 17:18).

What is special about the ketores? 

The Zohar (II:218b) explains a number of spiritual benefits that the Ketores bestows:

One who smells the burning incense as it ascends experiences a great clarity of purpose and joy, and an expunging of the evil inclination.  The ketores has the ability to shatter the sitera achara. The Ketores was used to stop plagues and whomever meditates on the Ketores will be protected from various calamities and noxious evil forces.  The Zohar describes a meditative process where the smoke materializes into various unifying forces for G-d’s name, and therefore confer spiritual and material blessings upon those who gaze and contemplate the Ketores.

The Ramah (Toras HaOlah III:17) also discusses unique features of the Ketores.  Since it was only made available to those who never performed the service before, there was a voluntary open emotional state attached to it. Like the wisps of smoke themselves, they are open to the subtle influence of the wind, instead of coming from strong internal bias.  This is why it was a segulah for wealth, because it engendered a state of peace and well-being. 

While much of this remains a mystery, let us try to figure out some spiritually unique aspects. The Ketores consisted of a formula or combination of various herbs, which alludes to the idea of the necessary focus and balance of various drives within a person and the community that need to combine to serve Hashem. This is particularly meaningful in that one of the herbs had a noxious odor, the Chelbana, as if to say all parts of the person and the community is welcome (Kerisus 6b). Another factor to consider is that since it is an odor, and fully consumed, it is the closest physical representation of a spiritual offering. In art we might portray a soul as a glowing halo. Who knows what a soul really looks like, but something glowing and translucent is a good way of representing a spiritual manifestation. The clouds and smoke of the incense are similar. Watching how it winds its way up to the heavens can be arousing and meditative as well, which is alluded to in the Zohar we quoted above.