flexible text animator

Does anyone have a good approach to flexible text animation?
For example to count up or down between 0 and  1,000 with formatting and font choices
Or to go from $0 to $2.5 Billion  or $0 to $250,000,000
and a similar effect from random text characters - maybe like an old fashioned airport departure ticker board -
to end with "Special Offer" for example?