Is there a way to add something in-game that would allow people to be able to type in the warp some where you can see it in case you forget? Like, a warp notepad, or something of the sort?

Just use Notepad xD or Word lol.....or write it in a notebook? You're on a computer <3

It's called a 3x5 card and a pen...

I'm not sure exactly what you are asking so I will answer the possible two questions I see here:

A) I use this fantastic mod: The Minecraft Macro/Keybinding mod

It allows you to set hotkeys. I have my numpad keys for all the warps I frequently use (as well as /home, /chest, /craft) and I also have the '/' button that prompts for a warp from a list I use sometimes. Check it out, it is imho the best MC mod ever.

B) Have you checked out the warp lounge (/warp warplounge) it has signs for warps all over MT. I'm sure you can /pe for a warp to be added to it or for a MyWarp sign to be put where ever you want.

I'm going to +1 this because it made me lol but physically writing down warps is a waste of my time xD

i use my minimap mod to save waypoints at every warp i make

I mean something in-game that you could type in or check your warps, So you don't have to write it down or open a document every time you forget a warp.

no...best to just keep a notecard with your computer/lappy cause if there was, there is always the chance of it being lost anyways in game.

all warps are listed ingame however. Alphabetically...just type /warp list to display, then /warp list # to go to a page of listings

Warp list goes alphabetically, and it has 400 or so pages. You would have to take a while to track down the specific warp, and then remember the page number if you forget it.

Seriously, that mod is probably exactly what you need. give it a once-over!