Go here to see the list of minor league free agents.  No exciting finds stuck out in that listing.  Just for your information, here are the minor league free agents who played for the Astros last year:

Houston Astros (25)
RHP: Erick Abreu (Hi A), Jack Cassel (AAA), Ron Chiavacci (AAA), Chance Douglass (AA), Paul Estrada (AA), Bo Hall (AA), Ryan Houston (AAA), Kyle Middleton (AAA), Josh Miller (AAA), Jose Oyervidez (AA), Nick Regilio (AAA)
LHP: Doug Arguello (Hi A), Ray King (AAA), Mark McLemore* (AAA)
C: Julian Henson (Lo A)
2B: Richard Paz (AAA)
3B: Rob Cosby (AA)
SS: Osvaldo Fernando (AA), Danny Klassen (AAA), Roberto Mena (Hi A)
OF: Jarred Ball (AA), Nick Gorneault (AAA), Val Majewski (AAA), Ray Sadler (AAA), Todd Self (AAA)

By the way, I thought Todd Self decided to go into coaching in the Astros' minor league organization this year.  Maybe he still has the bug for playing.

As I said, I don't have any exciting finds. I do see quite a few ex-Astros on this list. Maybe Baseball America or somebody else will write up a more thorough review of the list and come up with suggestions.

Guessing that the outfield and middle infield might be a possible area where a minor league free agent might have an opportunity to compete for a utility back up position, here are a couple of long shot ideas: John Rodriguez, Tony Graffanino, Callix Crabbe, Rob Mackowiac.