Very new to the Arduino.
I am wanting to make use of the 25 RGB LEDs that I have.
One possibility is to put them in a 5x5 matrix and use shift registers to control them similar to: Overview | Arduino Lesson 4. Eight LEDs and a Shift Register | Adafruit Learning System
Are there other projects that can make use of these RGB LEDs that would be fun to build?
How you wire them up, and how you physically arrange them, can be two different things.
For example, you can wire them up as 5x5 matrix, and arrange them that way, with the LEDs in a nice compact square, and create a little animated screen, or scrolling text, a little display.
Or you have them connected to the same control logic, but spread them out in a long string with longer wires, maybe as two circles representing the 5 minute/1 hour intervals of a clock,
or some other pattern that makes up a game, or a decoration of some sort.
sort of ambi light for a TV set?