The ability to set prices in different base currencies for different products
There are some country-specific or provider-specific products and services with prices fixed in different currencies. They should not change at all and should not be influenced by exchange rates. Since in WHMCS we can define only one default (base) currency, there's currently need for almost daily manual pricing updates for such products.
WHMCS set up with Euro as the base currency. Domain registrar's pricing is based on USD (the price in USD never changes, but their EUR fluctuates). Web hosting provider is based on EUR, that's cool in our case. For Serbian market, we offer .RS domain registration where the prices are fixed in RSD and should not follow exchange rates.
If only I could explain to WHMCS, per domain/product/service, which currency to use as a base for calculations and never touch the amount defined for that currency automatically..