Our Company's standard operating procedure for the B-757 states a maximum taxi speed of 20 kts forward in a straight line, and 10 knots while turning. Speed can be monitored on the IRS G/S read-out.
I think most large jets use similar criteria. And as posted above, whether it's an ultra-light or an ultra-heavy - one must always be able to stop quickly. So every situation is different - slipperiness of taxiing surface, slope, weather conditions, whether on a ramp or long taxiway, etc.
Hope that helps,