The mixolydian mode is one of my favorites to play in, and I often mix it with the pentatonic minor. Learning it definitely improved my playing a lot.
The Beatles used the mixolydian a good bit (Norwegian Wood, She Said She Said, Taxman, etc). The Stones' "sympathy for the Devil" is mostly in mixolydian with some pentatonic in it, as is Cream's "I Feel Free". BB King plays in the mixolydian mode a lot too.
The mixo-blues is essential too for playing acoustic country blues-style licks, such as Lightnin' Hopkins, Son House, etc.
And the mixolydian works great for jazz, when you add a raised 7th to the mixolydian, you get the dominant bebop scale.
Electrics: Epiphone Les Paul Standard (w/S.D. pups - JB-4/bridge, SH-'59 neck), Fender Fat Strat (Mexican), Squier Fat Tele, Squier '51, Agile Valkyrie III, Ibanez Artcore AF75, Washburn OS OE30 Delta King, Dean Vendetta XM (w/ Dimarzios, D-Sonic/bridge, Air Norton/neck), Silvertone archtop (late 60s/early 70s), Titan EG-1 strat, Gibson G-3 bass, Fullerton strat
Acoustics: Sigma DM-5 (Japanese), Silvertone archtop (early 50s), Yamaha FG-110 (Korean), Alvarez RD20 12 string, Silvertone (60s)
Amps: Alamo Capri (early 60s tube), Alamo Challenger (late 60s tube) Epiphone Valve Jr. Head (w/Peavey 1x10 cab & Realistic 2x6 cab), Fender Yale Reverb, Vox Pathfinder 15R, Marshall Lead 12, Behringer G110 V-Tone, Marshall MG15CD, Vox DA-5, Pignose 7-100, Marshall Bass 12