My GM screen is my laptop cover, because I do almost all my GM-ing from the laptop these days. The rare times I'm working from published (paper) materials, I may need to hide things from the players, so sometimes I resurrect my Star Frontiers screens. (Yes, I am that old...) They're more appropo than AD&D screens.
The one regret I have about T20, actually, is that it isn't available electronically. In my D&D campaign, I've taken the SRD [System Reference Document, the electronic version of the core rules] and modified it heavily for my system, fleshing it out to include things like the experience point table and such - the things they deliberately left out so you'd have to buy the Player's Handbook and other rulebooks.
It'll actually be a difficult adjustment for me to go back to using a rulebook.
I also use MS Excel to do my dierolling. You have to have the proper add-in to actually have the randbetween(val1,val2) command, but if you have it, you don't have to parse a rand value to the particular die type. The moral of this story? Always do a full install of MS Office products.
Anyhow, my spreadsheet has a section for initiative values, which I type in each combat next to PC names and monster identifiers, and then run a reverse sort to *poof!* put them in order. There's another section for different die combinations, mostly repeated multiple times. For example, I have about 14 lines of randbetween(1,20) so I have 14 attack rolls, critical followup rolls, saving throws, etc. I have 1d6 rolls up to 20d6 rolls (and multiple iterations of those), and other combinations.
It *really* speeds up combat when I can just go down the list and pull up however many rolls I need. It's also nice when I don't want them to know how many dice the enemy wizard's throwing. A 8-level wizard who rolls really well - say 39 on 8d6 - seems more dangerous than if I'd tossed 8d6 and given them the result. Likewise, a 15-level wizard who rolls bad on one spell might seem less dangerous than one for whom they can hear the cascade of 15d6 hitting the table.
Keep 'em guessing, always!
Of course, in T20, I'll have to redo the layout for the die types the weapons use, but that's always fun.
Anyone who wants a copy of the dieroller spreadsheet, just email me (david@princelian.com). You'll need Excel to use it, with the Analysis Pak add-in, I think.