H/Tonks... not really interested in that pairing. It was interesting the first time I read it, and then quite meh.
H/Bellatrix... have to agree with ndf on that one. I don't understand the interest in the pairing. Especially given her portrayal in OotP. H/Narcissa on the other hand, there's been one or two that I liked.
Narcotic Effects is one of those, in case you haven't read it.
H/Fem!Blaise... I've liked that pairing for a long time, and it's mostly because of one fic. The Blaze of Blaise Zabini. Unfortunately, the author took it down a long time ago in order to rewrite it to accomodate OotP and barely got through 10% of the the story in the revised vision. Yuck. I'd kill for a copy of the original, but no one is likely to have it. Beyond that, there aren't any long H/Blaise stories worth reading, except for C. Night's
series. Unless you like first year AU stories.
Incidentally, sloth's
HP&T Undead Alliance is a Harry/OC Slytherin, and somewhere in there he states that the OC was originally Blaise Zabini until the issue of Blaise's gender came up.
Oh, and I'm sure you've read
Draco664's Apprentice/Journeyman Potter. Although certain events in the second story seem to imply that Harry will not completely reconcile with Hermione and the relationship may settle down into just H/Blaise.
For Harry/Padma, beyond the ones mentioned in this thread, there are none that I know of. Except for one.
HP&T Fall of Childhood. And the problem with this one is that it's not H/Padma all the way through - they break off at some point and he ends up with someone else, I think. It's fairly old, and so it's been a long time since I've read this.
For Harry/Pansy, there's really only one, and I think it's been listed above. However, there is this
thread you can look through. Don't know if any of those are worth reading, though. Oh, and there's one other - which I slightly dislike because of the harem setup, but really is mostly due to my distaste for Ginny -
HP&T Shades of Grey.
Also, there was at least one interesting H/Pansy story that I found on a livejournal somewhere. I don't expect to find it again anytime soon, however, as I probably had it bookmarked sometime before I wiped my hard drive.