You can auto log with MUSH. And I have been told you can get spell check as well, somehow. If you press ALT+3 you bring up the logging menu. Check log output about half way through the window and then set up where you want the file to go. I made a special folder for mine so it looks something like:
C:\Documents and Settings\Randy\My Documents\SKz\%a%d%b%Y.txt
The last part of that names the file after the day of the week, the date number, the month, and the year. If you don't set up something like it will keep logging in the same file and it becomes very hard to search back through them. I originally had it just say the day, the month, and the year, and every friday, for example, it would log all of my stuff in the friday file.
I have no idea how to get the spell check working, though. And I am sure you have noticed that until you pay for mush client, you have to wait for the timer. I have both MUSH and zMUD, and I use MUSH more or less because that is what I have used since I started playing SK. zMUD has much more to play with, but I don't even know if I'd ever really use it.