I was my friend amy's maid of honor last year - it's a lot of work but totally worth it to play such a big role in the wedding of a good friend.
you are in charge of a shower and bachelorette party, but you can certainly enlist the other bridesmaids to help you. There may also be a shower hosted by one of her relatives, where her mom's friends and female relatives will come. That one will likely be more formal, so have fun with yours. I had mine on the back porch of my parent's house, played music, had games, etc. Pretty simple food - fruit, veggie trays, homemade brownies and cookies, punch, coke. All pretty easy and I got my little brother and parents to help. My uncle manages some nurseries so he brought me LOTS of roses and I put them all over the room - fresh flowers really dress up a room. I also tacked up streamers and balloons - really inexpensive but pretty.
Go to your library and check out books for free instead of buying one.
Also don't be surprised if you are entrusted with holding important stuff on the big day - i had to hold the ring for amy's husband ALL DAY long on my thumb PLUS her engagement ring on my finger. i was scared to death i was going to lose something. I also smoothed out her skirt after her father gave her away and held her bouquet during the ring exchange.
The best man traditionally gives the wedding toast, but you may get to say a few words too. I was there when Amy met her future husband, so I told the story and gave them a nice little toast right before their first dance.
There, I think that's all - except the biggest job of all - giving lots of hugs and a listening ear when the poor bride is stressing out AGAIN and AGAIN. You're the designated emotional support.
