No matter what series you watch, your favourite character will always resemble a character in a different series. Miroku's no exception here, of course, and there are a number of other characters in anime and manga that really resemble our letcherous priest. :3 Below you can find the characters that I've thought of!

Nicholas D. Wolfwood (Trigun)
The first character that comes to mind when thinking about Miroku is Wolfwood. Both are priests (although of different religions) but they both don't act like priests should. Both Miroku and Wolfwood live fairly violent lives and they're both not very celebate (although Miroku's far more letcherous than Wolfwood ever is). The two of them even look similar to some extent, being tall with short black hair.

Ryouji Kaji (Shin Seki Evangelion)
Kaji and Miroku share quite a bit in common, both physically and in terms of personality... They both have short black hair with a small pony tail and they're both rather attractive. Both Kaji and Miroku are ladies men and have trouble with their objects of affection. Both of them are also not what they seem... they appear to be rather charasmatic but in their respective ways, they're both delinquents -- it's hard for the other characters in their respective series to figure out what they're up to at times.

Souma Shigure (Fruits Basket)
Aside from both Shigure and Miroku being rather perverted, both characters have something darker about them hidden under their pleasant exteriors. In Shigure's case, he's plotting something and in Miroku's case, he's a delinquent but both have very polite and cheerful personalities and it's rare that anyone sees their more devious side. As for looks, Miroku and Shigure do look similar, both being rather tall with short black hair and both wear yukata (though Miroku's yukata is covered with a robe).

Tasuki (Real Life)
Oh my god, it's me! XD I think the picture proves it all. I've asked a number of my friends if they thought I was similar to Miroku in terms of personality and they all said yes -- we're both perverse. Way to feed my ego, huh? ;P Seriously though, I think I'm a bit devious though most people who meet me see me as a charming person. I guess it's hard to compare myself to someone who is supposed to live in the Sengoku Jidai and has an entirely different lifestyle but I guess there's enough similarities to make my friends think of me when they hear Miroku's name. ^^;