Ah.... I'm guessing a word clock.
There are several instructable articles about this.
You can find many pages by googling around.
Here are a few links of what I think you are talking about:
Whether it is individual LEDs in word clock or segments inside 7 segment LEDs
it doesn't matter. The techniques for driving multiple LEDs with fewer pins
will be the same.
Using a technique called charlieplexing it is possible to drive 120 LEDs with a Arduino board
without having to resort to shift registers or other external chips.
The key is that not all of them are on at once.
The problem with trying to have a pin to drive each individual LED is that
even if you did by say using a Teensy++ the AVR cannot drive all the LEDs at once.
That is too much current. So you can't run them all at the same time even if you
wire up that way.
In the word clocks I've seen, the words need more than a single LED
to light up the full word. It often takes an led per letter
Words like "Minutes" will need 7 Leds. If the LED has much brightness to it,
which it will need to see in the daylight, the 7 leds will draw more current than
than the AVR pin can handle and you still need to light up a few other words
to show the full time.
So that means you have to use some sort of external circuitry and as well as multiplexing
to get the job done.
A lot of the word clocks only use 24 or so "words"
There are many techniques that could be used.
You could use shift registers or a matrix driven directly by pins.
But both of those will potentially require using transistors to actually drive the LEDs
especially if the the LEDS are not time multiplexed.
With that many LEDs, unfortunately, I think you are going to have
to jump into the deep end and start swimming.
The hc595 can drive 25ma per output but it can't do that on all 8
pins at once as the total package can only support 750mw which is about
18ma per pin if all are on.
You can limit the current to make that work, but it may not be as bright as you
Take a glance at some of the other projects to get some ideas as to what they have done.
They have schematics and even code.
Me, I'd do it with a matrix and a few transistors and time multiplex it.
It keeps the external components down to just resistors and transistors
which are pretty cheap.
For a clock "chip", you could go that route but then you would need more components.
I'd get an i2c clock module that is ready to go. Just pop in the battery and hook it up.
You can get it from Adafruit or if you have time, you can order a similar module
from China off ebay for less.