Yet another solution is to use script. You create an extra field called [Dirty] and through script update it with either a random number of the current time. This is called "dirtying the record." It is easy to implement. The [Dirty] field does not carry any supplemental information and is only a mechanism to get the record to change and trigger notification.
I would argue that any script technique is superior to all other methods mentioned here not because of its individual performance but because it will open up your world to what can be accomplish with script. All the other solutions require you to do one-off setups and don't substantially expand your capabilities or portfolio of skills. I say script everything!
