Artemis, goddess of the hunt and closely associated with Apollo, is quite common in classical sculpture, but can still be tricky to identify as she appears in two different costumes.

Artemis Verailles, Roman copy of a 4th century original (attributed to Leochares).
The first, and easiest to recognize, is Artemis as the hunter. You'll easily recognize this type by the short skirt (she is one of few goddesses that ever wear a short skirt), bow and arrows and she's frequently accompanied by a stag.

Artemis from ca 100 BC, dressed in a chiton, peplos and himation.

Bronze from the 4th century BC.
The other type is Artemis as a maiden, as she can be found in e.g. Brauron. Here she's dressed in a long dress, but still with the arrows.

Here you see Mars as he was thought of in the 2nd century AD (If I remember this correctly).

This is a modern copy of a statue from at Hadrianus villa, but it's a good representation of Ares as youth.
The Greek Ares, associated with the Roman god Mars, is very rare in sculpture and you're really lucky if you run into him. I could only find two examples; one at Hadrianus villa (Tivoli) and one at the Monte Martini museum at Rome. It is however easy to recognize the god when you see him, he's portrayed in arms as bearded in early art (archaic) and as a naked youth from the classical period and onwards.

Athena must have been one of the most popular gods to represent in sculpture during antiquity, it's not uncommon that large museums have not one but several different pieces - the national museum in Athens have a room with only Athena statues, Glyptoteket in Copenhagen have at least four pieces and so on.
It is also very easy to recognize Athena, which of course helps us noticing her. She's normally the only armoured female god, she's wearing an Aegis (a piece of armour covering the upper torso, with a gorgons head in the center) and commonly a crested helmet. She is also often seen with a shield at her side and sometimes a snake or owl.
You might want to compare the picture above with the one of Athena Parthenos (a 2nd century ad copy) or a Hellenistic bronze Athena from Piraeus.

Apollo, crudely dated by the Carlsberg Glyptotek to 30 BC-500 AD - I would guess narrow it down to 30 BC-235 AD.

Apollo from at temple at the Athenian Agora, 4th century AD, possibly a work by Euphranor.
You can be almost certain that you will find a statue of Apollo if you visit a museum of classical art or history - he is one of the gods that you'll keep running in to.
He's also easily recognized with his rather female forms and his lyre, an instrument that he almost always carry. There are however types that doesn't fit in to the norm, such as Apollo from Olympia, where we see him depicted in a stiff position, on top of the situation, as if he can't be seen by the fighting centaurs and Lapiths.

Apollo from Olympia (ca 460 BC).

Here (lat. Juno) is quite uncommon in sculpture, I can only come up with two examples that I have seen (I'm sure that I've forgotten a dozen thou).
It must also be admitted that Hera isn't the easiest goddess to recognize. You can however look for a royal female with a crown and sometimes a pomegranate.

The Roman emperor as Jupiter (Zeus), 2nd century AD. Found next to the stadium in Isthmia.
Zeus (Jupiter) is, of course, the king of the gods and the son of Kronos (Saturnus). He's, however, not the most common god to be found in sculpture, even thou you'll see him from time to time - you might compare this with the fact that he has no major temples on any city acropolis and only a few festivals in his honour.
Zeus can be recognized by several traits: he's always bearded and you'll normally find him sitting quietly on a throne with a sceptre in his hand (probably on the model of Pheidias statue). You can also find him flanked by an eagle from time to time.
Other statues of Zeus:
Zeus and Ganymede
A throned Zeus with Cerberus (This is however most likely a Serapis in original, a god closely connected to Zeus).
Upper body of Zeus

The gods going into battle vs. the giants, a so called gigantomachy. Here you see Heracles to the left (in his lions pelt), then Dionysoswith his panther skin and wagon drawn by the same animals and thereafter Apollo and Artemis with their bows. Many other gods are involved in this battle, but not seen in this shot. Relief from the treasury of the Siphnians at Delphi, late 6th century/early 5th.
Well it's time for a new theme, the last one has been going on long enough, and I would like to focus on the Greecoroman pantheon and how these are represented in sculpture - thus expect a lot of statues for a while. Remember that even as I use a lot of printed material as sources to write these posts (such as the Oxford Classical Dictionary, Dictionary of Greek and Roman Biography and Mythology and a number of books written specifically on ancient religion and art) will much of what I present come from my own experience of ancient sculpture.
I would also like to add that I am perfectly aware of the dangers of talking about the Greek and Roman gods (as an example, Zeus and Jupiter) as the same entities, but it should be manageable as long as I do not wander of too far into mythological details - the focus is on the artistic representation in antiquity not on the origins, specific cults or epithets. Only gods that I've got found in classical sculpture will be represented here.
Apollo
Artemis (Diana)
Ares (Mars)
Asklepius
Athena (Minerva)
Charados (A greek flood god)
Demeter (Ceres)
Dionysos (Bachus)
Tyche (Fortuna)
Helios (Sol)
Hera (Juno)
Hermes (Mercurius)
Hygieia (Sirona)
Kybele (Magna Mater, connected with Rhea)
Mitheradates
Muses (connected with the Camenae)
Nike (Victoria)
Pan (Inunus or Faunus)
Persephone (aka Kore; lat. Proserpina)
Poseidon (Neptune)
Serapis
Zeus (Jupiter)

Some finds are very difficult to store. Here you see one solution used at Amathous where all the loose drains have been placed in one corner of the site - I really hope that the documentation was done properly.

Funerary stele, 6th century BC, from the necroplois of Kition.
This stele is interesting as it is in the shape of a lotus flower, a fairly popular flower in ancient culture. You can, as one example, find it, being eaten by bulls, in pottery paintings.

Head of a wreathed, bearded man. Limestone from Arsos, ca 480-450 BC.
It is always interesting to see how certain types of statues show up again and again. Here we see a head of a male, which is looking very much like the one posted about a month ago.
Another interesting feature is the very faint red colour on the beard and curls, could it be traces of the original paint?