Here's some modes with 7 notes, to test before any abusive use...
You will find :
The Bartok mode
C, D, E, F#, G, A, B.
It is the 4th degree of the melody minor, which is very much used, that is why I announce it (even if it belongs of the "known" modes). Think mixolydien (G mode) with increased fourth.
Chords : C 7 (9, #11, 13).
Super-locrien mode (or faded mode)
C Db Eb Fb Gb Ab Bb C.
7th degree of the melody minor, you can represent a major range with the tonic gone up of a semitone (just let you represent it, because if you think about it that when you play, you could get catastrophes...). This mode works very well on a 7#5 chord, because the Fb is equal to E and Ab is equal to G#.
Chords : Cm7b5 (b9, b11, b13) or C 7#5 (b9, #9, #11).
Hungrian major Mode
C, D#, E, F#, G, A, B, C.
Related to the Bartok Mode, with an increased 2nd
Chords : C 7 (#9, #11, 13).
Hungrian minor Mode
C, D, Eb, F#, G, Ab, B, C.
Looks like the ?melodic minor? with increased 4th.
Chords : C min/maj7 (9, #11, b13).
Oriental Mode 1
C, Db, E, F, Gb, A, Bb, C.
Think locrian (B mode) with a major 3rd and a major 6th.
Chords : C Maj/min 7b5 (b9, 11, 13).
Oriental Mode 2
C, Db, E, F, Gb, A, B, C.
Strange, 4 half tones like in the previous one, the chord is great, but I don?t use it.
C Maj7b5 (b9, 11, 13).
Oriental Mode 3
C, D#, E, F, Gb, Ab, Bb, C
A ?kind? of faded mode that I?ve also never used. (If someone use it, talk !).
Chords : C 7b5 (#9, 11, b13).
Arabian Mode
C, D, E, F, Gb, Ab, Bb, C
It is also called Locrian Major, because it starts as a major scale and ends as a locrian (or as an faded) mode.
Chords : C 7b5 (9, 11, b13).
Enigma Mode
C, Db, E, F#, G#, A#, B, C
Closed to be a full tone scale, except for the 2nd minor and the 7th major B/C.
Chords : C Maj7#5 (b9, #11, #13).
Napolitan Major Mode
C, Db, Eb, F, G, A, B, C
Think about Melodic minor mode with an 2nd minor. The ?Major? is at the end of the scale (from F to C, this is the end of a Major scale).
Chords : C min/Maj 7 (b9, 11, 13).
Napolitan minor Mode