There are two ways I know of to ease the burden on the captain. One is Tennisone.com, which most TW captains seem to use. Every player can log on and indicate their own availability and see schedules/line-ups. It sends automated match reminders; players confirm on the site.
I have decided not to use Tennisone for teams I captain (although my mixed captain uses it). I don't like that it sends reminders to everyone on the team, even if they aren't playing. I don't like how you have to do so much clicking around to see what is going on. And as a captain trying to do a line-up, I wouldn't like how players can list their availability as "?", which is utterly unhelpful.
I use a Google on-line spreadsheet instead. It is the team central repository of information. I have sheets for the line-up, the contact list, helpful links, partner groups, practice availability, and match locations. I like doing it this way because it is one-stop shopping. Once you bookmark it, you just click on the bookmark and the entire schedule/line-up pops up, with everyone's availability. No clicking around.
Google spreadsheets allows lots of flexibility. For a tricky match location, I can add "If you get to the fire station, you've gone too far." After each player's name in the line-up, I put a number that indicates how many matches they've played so far so I can keep things even. If someone cancels, I can indicate that they've canceled and so-and-so is subbing in. If we get a warm-up court or are on clay, I can indicate this also. Once a match is played, I can gray it out so players can focus on the matches remaining.
Each player has a log-on and can edit the spreadsheet. The way I handle it is that their sole responsibility is to list themselves as unavailable for matches they cannot play.
Also, my approach to doing line-ups is that I can put you in the line-up if you haven't listed yourself as unavailable. If I schedule you and you later can't play, then that match still counts against your allotment of six matches. Silence = "I'm available!", so players are very diligent about making sure their unavailability is reflected on the spreadsheet so they don't have to cancel and lose out on their full allotment of matches. I don't have to deal with lots of "?".
The disadvantages of my system are: (1) I have to send my own match reminders via e-mail and players confirm directly back to me; (2) there are some people with no experience with Excel who *freak out* at the idea of a spreadsheet; and (3) a player can accidentally delete information others have entered. I keep back-up copies of the spreadsheet, and so far I haven't had any insurmountable problems.
There you go!
