Simple actions, based on coroutines and callbacks. Delays, loops etc...

CoroutineExtensions.cs

using UnityEngine;
using System.Collections;
using System;

public static class CoroutineExtensions {

	public static void StartWaitForSeconds(this MonoBehaviour target, float seconds, Action completion) {
		target.StartCoroutine (WaitForSeconds (seconds, completion));
	}

	public static void StartWaitForSeconds(this MonoBehaviour target, float seconds, Action start, Action completion) {
		target.StartCoroutine (WaitForSeconds (seconds, start, completion));
	}

	public static void StartLoop(this MonoBehaviour target, float interval, Action action) {
		target.StartCoroutine (Loop (interval, action));
	}

	public static void StartLoop(this MonoBehaviour target, float interval, Func<bool> condition, Action action) {
		target.StartCoroutine (Loop (interval, condition, action));
	}

	private static IEnumerator WaitForSeconds(float seconds, Action completion) {
		yield return new WaitForSeconds (seconds);
		if (completion != null)
			completion ();
	}

	private static IEnumerator WaitForSeconds(float seconds, Action start, Action completion) {
		if (start != null)
			start ();
		yield return new WaitForSeconds (seconds);
		if (completion != null)
			completion ();
	}

	private static IEnumerator Loop(float interval, Action action) {
		while (true) {
			yield return new WaitForSeconds (interval);
			if (action != null)
				action ();
		}
	}

	private static IEnumerator Loop(float interval, Func<bool> condition, Action action) {
		while (condition ()) {
			yield return new WaitForSeconds (interval);
			if (action != null)
				action ();
		}
	}
}