There are two main types of lighting effect - (well OK, there are hundreds, but lets keep this simple

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In no particular order, theres the type which looks nice at the audience/dancers look at your disco. These include Light screens (bulbs in boxes), 4 way spot lights (either in vertical columns, or horizontally on the floor), star clothes, name lights, infinity/tunnel lights, LED lighting, silk flame lights etc..etc..
Then there are the lights which just look like boring metal rectangles to look at, but project coloured beams and patterns (known as Gobo's) onto the dancefloor, walls, ceilings etc. Such units include moonflowers, lasers, moving mirror, spinning barrel, or moving head effects. This effects also give off a mid-air "beams" or "ray" effect if used in smoke, or haze.
The second type of lights often come with DMX (a lighting "control language"), which enables units to be controlled, and synchronised, with respect to colour changing simultaneously, or pattern/gobo changing in sync etc. Some cheaper lights offer a Master/Slave option to accomplish the same thing, but some are often using their own special language/signals, rather than a standard, like DMX.
It should be noted that many of the second type of lights require a hazey or smokey atmosphere. However, not all venues allow smoke, or even haze. I play one venue which has optical smoke alarms, even a rented haze machine with the lightest "weight" of haze fluid, on the lowest practical setting, triggered the smoke sensors. Such venues often fall foul of their insurance policies if they turn off, disable, mute, or exclude a zone (EG: The function room) on their alarm panels, so you may find that a smoke machine, and lighting that relies on a mid-air effect is a waste in such venues.
Also, be sure to look for lighting which will compliment both faster/hectic parts of the music, as well as the slow songs, or instrumental breakdowns/ambient sections of dance tracks. Nothing makes me cringe more when Im out (as a guest) to be doing the ol' cuddle-n-turn-around-slowly-with-your-eyes-shut dance, with 4 whopping great spinning barrel effects giving my partner and I a suntan.
Also, although its down to opinion, its more versatile (In my opinion) to have say, 6 x $100 lighting effects, than 1 x $600 lighting effect. The audience would get bored with the same lighting running all night long. Besides some (most? Chris?) lighting have "Duty cycles" listed in their manuals eg: To be used for 10 mins in every 20, or "5 mins on/10mins off" etc. Such duty cycles are often(?) quoted to prolong the life of the bulb and the effect.
Remember too with lighting that you can only run so much off of a domestic wall socket. Here in the UK, you can pull 3120 safely out of a standard wall socket. So, switch on 8 x 500 watt flood spots at once, and you'll probably loose a fuse somewhere. I dont know what limits there are where you are.