Hey, question! I vote for several of my favorite webcomics on TopWebComics.com every day. Like, religiously. I even vote twice some days, when I remember to vote from my cell phone (completely allowed, by the way :)
Modest Medusa actually DOES have a voting gateway set up for it, here:
http://topwebcomics.com/members/votefavorite.aspx?id=12150About 1000 votes (total for the month) would get you on the first page (Top 100) easily, and probably ranked up in the 50s.
Would you consider asking readers to vote on TWC, maybe starting in April, and see how it goes? Seems to be a no-brainer: free advertising, possible influx of new readers. And with how ferociously supportive your current readers seem to be with MM, I think it could work out really well for ya!
Whether you decide to try the TWC thing or not, I wish you continued success, and I can't wait to see what happens next!