To continue a conversation:
* Regardless
* In any case
* Nevertheless
* Nonetheless
* At any rate
* However
* Still
* Yet
To change the subject:
* So
* Well
* Speaking of which...
* Moving on...
To emphasize a point:
* In fact
* Actually
* As a matter of fact
To dismiss a topic:
* Never mind
* Forget it
* That's beside the point
* It doesn't matter
To introduce a contrasting point:
* But
* On the other hand
* Conversely
To conclude a thought:
* Finally
* Ultimately
* In the end
The best alternative for you will depend on the specific situation and the tone you want to convey.