For a while I've kept a text document for each deck I build (that I have to order cards for), I try separating by card type and organizing by mana cost but it would definitely be easier if I used a site made for this task.
It'd be great if it also:
Supported other card games (Pokemon and Flesh and Blood)
Could export a deck to a text list (Mostly for proxying (are we allowed to talk about proxies here?))