Hopefully the attached files can help you organize your events.  The envelops are in MS Word, but will most likely work in Open Office or something like that as well.  You just need to do a search and replace to add your event information.
The round robin and playoff sheets are in .pdf format, and do have some fill-able areas if you wish to customize for your event.

Envelope Labels – 5×7
Envelope Labels – #10

Round Robin Sheet

Knockout – 4×1
Knockout – 4×2
Knockout – 4×4
Knockout – 8×1
Knockout – 8×2