Revered by all religions of Hinduism. This is the primeval sound Om. This mystic sound is so important that there are few worship without this. The archanas done at the Hindu temples include this for each of the mantra chanted. The holy vedas also start with this. This mantra is one of the renowned mantra for meditation. This sound represent the Supreme Divinity.
The prime symbol of worship for Shaivites. (In fact the name itself means symbol). This is broad in the middle and conical towards the top. This is the form of flame. In Shaivite philosophy the God is formless. Due to the Grace on the souls for the easy comprehension of the Divine and liberation the God appeared in the form of a Flame. This flame is what is worshiped as lingam in stone and other forms that make the worship easier. This is considered more sacrad than form worship by Shaivites.
The three bands one could see on the foreheads of the gods and goddesses. This three bands are worn by the Shaivites and the other religions in that family (shakta, kaumAra, gANApatya). This symbol is called tripunDra (three band). As the God appeared as a Supreme Flame (This need not be confused with agni. agni becomes one of the aspects of God but not the Supreme itself), in the Shaivite religion, (refer to lingam above) naturally Ash becomes the symbol that indicates the association with that param jyoti (Supreme flame).
rudra + axa translates to the eye of rudra. This is a beed from a tree. This is considered to have emanated from the eye of Lord Shiva when He burnt the tripura asuras. This is one of the holy symbols worn by Shaivites along with Holy Ash. This is worn as a single beed or as garlands of beeds.
This is the dot most of the Hindus have at the eye-brow junction. This could be of sandal or red kumkum or a mix of both. This junction is one of the very significant chakra, called in spiritual terms AGYA chakra. This is a very sensitive point. So the tilaka is kept at this point.
The vertical three lines (or at times single red line) that is worn by the Vaishnavites is called shrI chUrNa. The two outer lines will be in the white color and the middle one in the red. The red line is normally with kumkum or the red sand at the base of the tulsi plant. This custom has been introduced in the later parts of time by rAmAnuja as vaiShNavite symbolism. vaiAhNavas not belonging to rAmAnuja sampradAya (for example mAdhvas) do not follow this custom.
This is the Holy Bull - the vehicle and the flag of Lord Shiva. So this is the emblem of Shaivites. On the wall of the Shaivite temples, in the flags, in the message headers and many other articles this emblem could be found. The ancience of this emblem will be very evident from the fact that this emblem has been found in the excavations of harappa mahanjadaro (the so-called Indus valley civilisation sites). According to Shaivite scriptures bull represents the dharma (justice).
The tri headed spear (trident) - one of the renowned weapon of Lord Shiva. So this is the second important emblem of Shaivites after nandi. As the Goddess shakti also holds this trident, this is the symbol that is held high by the devotees of shakti as well.
The counch called pAnchajanya and the disc called sudarshana in the hands of Lord ViShNu are the important symbols of Vaishnavites. These two are printed as emblems in the artefacts associated with Vaishnava.
The spear is the renowned weapon of Lord Skandha. So this is a very respected symbol of the devotees of Lord Subramanya.